In this paper, we proposeR3: LearningReasoning throughReverse CurriculumReinforcement Learning (RL) , a novel method that employs only outcome supervision to achieve the benefits of process supervision for large language models. The core challenge in applying RL to complex reasoning is to identify a sequence of actions that result in positive rewards and provide appropriate supervision for optimization. Outcome supervision provides sparse rewards for final results without identifying error locations, whereas process supervision offers step-wise rewards but requires extensive manual annotation.R3overcomes these limitations by learning from correct demonstrations. Specifically,R3progressively slides the start state of reasoning from a demonstration’s end to its beginning, facilitating easier model exploration at all stages. Thus,R3establishes a step-wise curriculum, allowing outcome supervision to offer step-level signals and precisely pinpoint errors. Using Llama2-7B, our method surpasses RL baseline on eight reasoning tasks bypoints on average. Notebaly, in program-based reasoning on GSM8K, it exceeds the baseline bypoints across three backbone models, and without any extra data, Codellama-7B +R3performs comparable to larger models or closed-source models.111Our codes and data are available at Github :https://github.com/WooooDyy/LLM-Reverse-Curriculum-RL.