Abstract: Objective: To study the role of ERK1/2 MAPK signal pathway in the proliferation-inhibitory effect of curcumin on A549 lung cancer cells. Methods: The proliferation-inhibitory effect of curcumin on A549 cells was assessed with method of MTT assay. Levels of ERK1/2,p-ERK1/2,TIMP-1 and MMP-9 protein expression were measured by Western blot. Results: Curcumin inhibited A549 cells proliferation in a dose-dependent manner. The level of p-ERK1/2、MMP-9 decreased,and the expression of TIMP-1 protein increased with the dose of curcumin but the expression of ERK1/2 protein had no change. Conclusions: Curcumin could influence the ERK1/2 MAPK signal pathway,induce the expression of apoptosis-related proteins and inhibit the proliferation of A549 cells.