Objective：To investigate the inhibition of procaspase-activating compound-1(PAC-1), Oxaliplatin（L-OHP） and PAC-1 conbination with L-OHP on  human colorectal cancer cell lines （HT-29，SW116，HCT116，SW620，SW480）.
Methods：MTT assay was used to investigate the proliferation of cells before and after single and combined drug use.
Results：Both PAC-1 and L-OHP had signficant high effect of inducing apoptosis and inhibiting proliferation on five human colorectal cancer cells on a dose and time dependent manner.The IC50 of PAC-1 on different human colorectal cancer cells had no statistical significance(P＞0.05); but IC50 of L-OHP on the 5 cell lines had statistical significance(P＜0.05). PAC-1 combined with L-OHP （dosing pump at the same time）had an antagonistic effect(CI﹥1).
Conclusions：Both PAC-1 and L-OHP can inhibit human colorectal cancer cell lines, but the susceptibility of individual colorectal cancer cell lines on the two drugs are different. PAC-1 combined with L-OHP has an antagonistic effect.