Abstract: Objective: To investigate the growth inhibition role of arsenic trioxide(As2O3) on human amalignant melanoma A375 cell, and observe whether Caspase-3 protein can be expressed in A375 cell after induced by As2O3 . To provide theory and experiment base for treament of malignant melanoma. Methods: The morphologic changes of A375 cells were detected by fluorescence staining, apoptosis rate of A375 cells was detected with flow cytometry. Caspase-3 protein was detected by immunehistochemistry in A375 cells. The expression of Survivin mRNA was examined by semi-quantitative RT-PCR. Results: As2O3 caused morphologic change of A375 cells by fluorescence staining. As2O3 promoted A375 cell apoptosis significantly. When A375 cells were treated with As2O3 in 5, 10, and 20 mol/L for 24 hours, the apoptosis rate was 7. 07%, 38. 66% and 4. 34%. Caspase-3 protein was expressed positively in A375 cells by co-culture with As2O3 . The expression of Survivin mRNA was inhibited by As2O3 . Conclusions: As2O3 can cause morphologic change of A375 cells and promote apoptosis happening. As2O3 can induce A375 cells to express Caspase-3 protein. As2O3 can inhibit Survivin protein expression in A375 cells.