Abstract: Objective: To investigate the antitumor effect and possible mechanism of AC-88.Methods: H22,Meth A,EAC cell bearing mice in vivo and LOVO,TYK,H22 culture cells in vitro were used to study the antitumor effect of AC-88 and Western-blotting was used to study Fas expression of T lymphocytes.Results: The antitumor rate of AC-88 250 mg/kg group on three types tumor bearing mice was 76.31%,73.52%,and 71.91%,respectively.The average tumor weight was lower than control group(P<0.01).The IC 50 of AC-88 on each type tumor cells was lower than 10 μg/ml in vitro.Fas expression of T cells was decreased in the same time(P<0.01).Conclusions: AC-88 has obvious antitumor effect and maybe through decrease T cell Fas expression.