Abstract: Objective:In order to investigate the mechanism of inhibition effect of a lipopetide Fengcin on patulin production of Penicillum expansum. Methods:HPLC was used to detect patulin content in every unit weight of Penicillum expansum mycelium. The expression level of two key genes(6-MSAS and IDH),which translated patulin in Penicillium expansum mycelium,were detect by SYBR GreenI real-time PCR under Fengycin-treated and untreated conditions. Results:With Fengycin treatments,not only the patulin content in every unit weight of Penicillum expansum mycelium but also the expression level of 6-MSAS decreased significantly. The expression level of 6-MSAS of Fengycin-treated group was 11% folds of control group. However,the expression level of IDH of Fengycin-treated group decreased slightly,which was not significant. Conclusion:Fengycin could inhibit Penicillium expansum from producing patulin by affecting the transcriptional level of 6-MSAS.