Abstract: Melamine in milk power was determined by gas chromatography-mass spectrometer(GC/MS) made in china. The results show that the method has a good liner range between 0.005 mg•L^－1 and 2 mg•L^－1, R2 is 0.999 7. The limit of detection is 0.001 mg•L^－1, the quantitative detection limit is 0.02 mg•kg^－1. The recovery for melamine is in the range of 94％-102％. The method has good sensitivity, selectivity and repeatability, which has been applied to the determination of melamine in milk powder.