Abstract: Objective: To investigate the anti-tumor activities of pyrazole derivatives against PC3,Bcap37 and BGC823 cells,and the mechanism of action.Methods: The inhibition effects of pyrazole derivatives on PC3,Bcap37 and BGC823 cells in vitro were tested through MTT colorimetric assay and the apoptotic morphology was observed by staining the PC3 cells with AO/EB.The inhibition effects of the compounds on the phosphorylation of Erk1/2 were determined by Western Blot analysis.Results: Pyrazole derivatives showed inhibition activities against PC3,Bcap37 and BGC823 cells in a concentration dependent manner;compound F could induce the apoptosis of PC3 and Bcap37 cells;Western Blot analysis showed that pyrazole derivatives could not inhibit the phosphorylation of Erk1/2 induced by EGF.Conclusions: Pyrazole derivatives can inhibit the activities of PC3,Bcap37 and BGC823 cells,and compound F may induce the apoptosis of PC3 and Bcap37 cells;pyrazole derivatives can not inhibit the proliferation of PC3 cell through Erk1/2 mediated signal pathway.