OBJECTIVE: To study protecting the native Sichuan crude drugs from mildewing and moth-eating by 60 Co-γ ray radiation. METHOD: Seven native Sichuan crude drugs were selected as samples, to optimise the radiation dose. After the samples were radiated, we observed the effects of radiation on protecting the medicines from mildewing and moth-eating, determined the growth-rate of mould, and studied the changes in morphology, toxicity and main active fractions. RESULTS: Compared with the controls, the morphology toxicity and main active fractions of the samples showed no changes after having been radiated with 8 000 Gy, which is the most effective dose for protecting the samples from mildewing and moth-eating. CONCLUSION: It is an economical, safe and effective way to protect the native Sichuan crude drugs from mildewing and moth-eating by 60 Co-γ ray radiation.