The method for determination of napropamide,metolachlor,butrlin and trifluralin in tobacco was developed.The sample was extracted by acetonitrile,purified with Carb-NH2 solid phase extraction,and quantified the 4 pesticides by GC/MS-SIM.The results showed that it could remove the impurities of pigment,lipin in tobacco using Carb-NH2 solid phase extraction.The sample liquid after purified was clear and translucent.Under these conditions,the average recoveries of 4 pesticides ranged from 81.8 % to 108 % at spiked level of 0.025 -0.5 mg/kg,and the relative standard deviations were 1.38 %-8.95 %.The detection limit of 4 pesticides ranged from 0.005 to 0.01 mg/kg.