OBJECTIVE To stud y the chemical cons tituents of n-butanol part of Qubai tablet and its pharmacodynamic effect on the model of de melanocyte. METHODS The n-butanol part of Qubai tablet was prepared. The chemical constituents were analyzed by ultra-high performance liquid chromatography-mass spectrometry （UPLC-MS）. Taking mice B 16 melanoma cells as the research object ，the de melanocyte model was established and divided into model group ，positive control different concentration groups（8-methoxypsoralen 10，50，100，150，200 μmol/L），solvent group （diluted with DMSO ）and Qubai tablet n-butanol part different concentration groups （10，50，100，150，200 μmol/L）. The number of cells were observed by inverted microscope ，and the cell proliferation rate ，the rate of melanin production and promotion rate of tyrosinase activity were also detected. RESULTS In the positive and negative ion mode ，53 compounds in the n-butanol part of Qubai tablet were preliminarily determined （29 in the positive ion mode ，33 in the negative ion mode ，overlapping 9），of which coumarins accounted for the largest proportion ， followed by flavonoids. The n-butanol part of Qubai tablet could significantly increase the number of cells ，which was positively correlated with the action time and administration concentration. It could significantly increase the proliferation rate of cells ，the rate of melanin production and promotion rate of tyrosinase activity （P＜0.01）. CONCLUSIONS Coumarins and flavonoids may be the material basis for the anti-vitiligo effect of n-butanol part from Qubai tablet ；anti-vitiligo effect of n-butanol part of Qubai tablet may be realized by promoting tyrosinase activity.