Objective:To evaluate the mechanism of licochalcone B induce mouse melanoma B16F0 cells apoptosis.Method: Effect of licochalcone B on proliferation of B16F0 cells was determined by MTT.Hoechst 33258 fluorescent staining were used to observe the morphological changes of apoptotic cell.Apoptosis was determined by staining cells with annexin V fluorescein isothiocyanate（FITC） and propidium iodide（PI） labeling.The mRNA expression levels of B cell lymphoma/lewkmia-2（Bcl-2） associated X protein（Bax） and Bcl-2 were detected using RT-PCR analysis.Changes of Caspase-9 and Caspase-3 were measured with fluorescence assay.Result: Licochalcone B（5-15 mg·L-1） can effectively inhibit B16F0 cell proliferation in a dose-dependent manner.IC50 was 11.3 mg·L-1

and cell obviously appeared apoptosis characteristics

with the concentration of licochalcone B increased

the apoptosis rate was increased

licochalcone B（10

12.5 mg·L-1） significantly lowered the mRNA expression levels of Bcl-2/Bax

and raised the expression of caspase-9 and caspase-3

licochaleone B（7.5 mg·L-1） cause the activation degree of Caspase-9 and Caspase-3 higher than 12.5 mg·L-1.Conclusion: Licochalcone B induce B16F0 cell apoptosis through mitochondria-dependent pathway.