ERNIE 4.5 21B-A3B is Baidu's efficient bilingual model — 21 billion total parameters activating 3B per token, optimized for Chinese and English across Baidu's massive production AI infrastructure.
ERNIE 4.5 21B-A3B is an AI model released 2025 by Baidu, a leading organization in large language model research. Baidu's ERNIE 4.5 21B MoE — efficient Chinese language model with broad knowledge and coding capabilities. With 21B total (3B active via MoE) and a 128K tokens context window, ERNIE 4.5 21B-A3B is designed to excel across a range of demanding tasks — from software engineering and mathematical problem-solving to multilingual content generation and long-document analysis.
ERNIE 4.5 21B-A3B employs a Mixture-of-Experts (MoE) architecture with 21B total (3B active via MoE). In a MoE design, only a subset of "expert" sub-networks activates for each token during inference — ERNIE 4.5 21B-A3B has 21B total (3B active via MoE) total parameters but uses only a fraction per token. This allows the model to store significantly more learned knowledge than a comparably-priced dense model. MoE architectures have proven effective at reaching frontier-level capability while keeping serving costs manageable — a key reason ERNIE 4.5 21B-A3B can be offered at the scale that platforms like LITHOVEX AI make possible.
As of 2026-10-16, ERNIE 4.5 21B-A3B by Baidu demonstrates measurable performance on standard AI evaluation benchmarks. On CMMLU (Chinese) — which tests world knowledge across 57 academic subjects from elementary to professional level — it achieves 81.2%. These scores place ERNIE 4.5 21B-A3B — at 21B total (3B active via MoE) of parameters — in a competitive position within its model class. Note that benchmark scores reflect controlled evaluation conditions; real-world performance varies by task, prompt design, and domain specificity.
The primary strengths of ERNIE 4.5 21B-A3B are: Efficient MoE: 21B knowledge at 3B inference cost; Good Chinese-English bilingual performance for its class; ERNIE license for research. These make it particularly well-suited for Cost-efficient Chinese-English enterprise apps, Lower-resource Chinese language processing. Users working on complex, multi-step problems benefit most from ERNIE 4.5 21B-A3B's ability to maintain coherence across long inputs and produce structured, verifiable outputs.
Like all current AI systems, ERNIE 4.5 21B-A3B has limitations: Smaller than 300B variant; Commercial terms. For production deployments, validating outputs against authoritative sources — especially for domain-specific or time-sensitive information — remains best practice. Baidu continues to improve ERNIE 4.5 21B-A3B through ongoing research.
ERNIE 4.5 21B-A3B is available on LITHOVEX AI with a free account. Unlike direct API access — which requires billing setup, API key management, and per-token charges — LITHOVEX AI provides a seamless browser interface with no setup required, making ERNIE 4.5 21B-A3B accessible to students, researchers, developers, and early-stage teams globally.
As of 2026-10-16, ERNIE 4.5 21B-A3B by Baidu demonstrates measurable performance on standard AI evaluation benchmarks. On CMMLU (Chinese) — which tests world knowledge across 57 academic subjects from elementary to professional level — it achieves 81.2%. These scores place ERNIE 4.5 21B-A3B — at 21B total (3B active via MoE) of parameters — in a competitive position within its model class. Note that benchmark scores reflect controlled evaluation conditions; real-world performance varies by task, prompt design, and domain specificity.
Mixture-of-Experts: 21B total / 3B active, efficient Chinese-English
The training pipeline for ERNIE 4.5 21B-A3B involves multiple stages: large-scale pretraining on diverse multilingual text and code corpora to develop broad world knowledge, followed by supervised fine-tuning on instruction-response pairs, and alignment techniques such as RLHF or DPO. Each stage refines the model's helpfulness, accuracy, and safety. Baidu's research team — based in China — has optimized ERNIE 4.5 21B-A3B for the specific capability profile described above.
Inference efficiency: ERNIE 4.5 21B-A3B at 21B total (3B active via MoE) is designed to deliver quality outputs at practical serving speeds. Its 128K tokens context window enables processing entire documents, multi-file codebases, and extended conversation histories — particularly valuable for contract review, technical documentation analysis, and codebase-level AI assistance.
Getting started with ERNIE 4.5 21B-A3B on LITHOVEX AI takes under two minutes. Follow these steps:
For best results with ERNIE 4.5 21B-A3B: provide specific, context-rich prompts; include examples when generating code; specify output format when structure matters; break complex tasks into focused sub-questions.
Integration with Baidu Search and Chinese internet services
Chinese-language content generation at production scale
Enterprise AI for Chinese businesses across all sectors
Bilingual customer service for China-facing applications
Knowledge retrieval augmented with Chinese internet data
Baidu is China's leading search engine and one of the first Chinese tech giants to invest heavily in AI, establishing its AI research center in Silicon Valley in 2013 under Andrew Ng. The ERNIE (Enhanced Representation through Knowledge Integration) model family, now at version 4.5, represents Baidu's flagship open-weight contributions. ERNIE models are optimized for Chinese-language understanding and generation, leveraging access to Chinese internet-scale training data. The ERNIE 4.5 family includes both dense and MoE variants, with the flagship reaching 300 billion total parameters. Baidu's AI products serve hundreds of millions of Chinese users through Baidu Search, ERNIE Bot, and enterprise APIs.
Funding: Public company (NASDAQ: BIDU, $30B+ market cap)
Founded: 2000, headquartered in China.
ERNIE 4.5 21B-A3B by Baidu competes in a field with several strong alternatives. Below is a detailed side-by-side comparison against commonly listed alternatives, using benchmark data and capability profiles in the catalog.
Both ERNIE 4.5 21B-A3B and the models above are available free on LITHOVEX AI — test them side by side on your real tasks before committing to a subscription with any provider.
ERNIE 4.5 21B-A3B is released under ERNIE Model License, which means you can download and run it on your own hardware. Below are the quickest ways to get started.
LITHOVEX AI runs ERNIE 4.5 21B-A3B on cloud infrastructure, so you can use it instantly in your browser without downloading anything, configuring drivers, or managing VRAM. Create a free account and start in under 60 seconds.
ERNIE 4.5 serves hundreds of millions of Chinese users through Baidu's ecosystem. The 21B-A3B variant balances quality and efficiency for production deployments across Baidu Search, ERNIE Bot, and enterprise APIs serving Chinese businesses globally.
ERNIE 4.5 21B-A3B by Baidu has the following version history and notable updates:
For the complete changelog and latest release notes, visit the official Baidu model page.