A method was developed for the determination of 20 phthatic acid esters in milk and dairy products by gas chromatography-mass spectrometry (GC-MS). Samples were extracted with n-hexane and separated on a DB-5MS capillary column (30 m × 0.25 mm, 0.25 μm). The injector temperature was 280 ℃,the interface temperature was 280 ℃, and the ion source temperature was 230 ℃. Under optimized conditions, the linear range was 0-10 μg/mL with a correlation coefficient greater than 0.9990. The average spike recovery rates were in the range of 80%-109%. The detection limits were respectively 1.0 and 0.5 mg/kg for DINP and DIDP and 0.05 mg/kg for 18 others. This method proved to be simple, rapid, sensitive, specific and accurate.