Objective To study the inducing differentiation effect of gambogic acid.Methods Inducing differentiation effect of gambogic acid were evaluated by proliferation,morphology and function of tumor cells.Results Hb content of K562 cell was increased,melanin content of B16 cell was decreased and proliferation of Bel 7402 cell was inhibited by gambogic acid.And Bel 7402 cell showed induce differentiation in morphology.Conclusion Gambogic acid has inducing differentiation effect on tumor cells.