ZeroSearch: Incentivize the Search Capability of LLMs without Searching
Authors: name: Hao Sun; name: Zile Qiao; name: Jiayan Guo; name: Xuanbo Fan; name: Yingyan Hou; name: Yong Jiang; name: Pengjun Xie; name: Fei Huang; name: Yan Zhang
Published: 2025-05-07 17:30:22

Abstract: Effective information searching is essential for enhancing the reasoning and
generation capabilities of large language models (LLMs). Recent research has
explored using reinforcement learning (RL) to improve LLMs' search capabilities
by interacting with live search engines in real-world environments. While these
approaches show promising results, they face two major challenges: (1)
Uncontrolled Document Quality: The quality of documents returned by search
engines is often unpredictable, introducing noise and instability into the
training process. (2) Prohibitively High API Costs: RL training requires
frequent rollouts, potentially involving hundreds of thousands of search
requests, which incur substantial API expenses and severely constrain
scalability. To address these challenges, we introduce ZeroSearch, a
reinforcement learning framework that incentivizes the search capabilities of
LLMs without interacting with real search engines. Our approach begins with
lightweight supervised fine-tuning to transform the LLM into a retrieval module
capable of generating both relevant and noisy documents in response to a query.
During RL training, we employ a curriculum-based rollout strategy that
incrementally degrades the quality of generated documents, progressively
eliciting the model's reasoning ability by exposing it to increasingly
challenging retrieval scenarios. Extensive experiments demonstrate that
ZeroSearch effectively incentivizes the search capabilities of LLMs using a 3B
LLM as the retrieval module. Remarkably, a 7B retrieval module achieves
comparable performance to the real search engine, while a 14B retrieval module
even surpasses it. Furthermore, it generalizes well across both base and
instruction-tuned models of various parameter sizes and is compatible with a
wide range of RL algorithms.