A GC-MS method was developed for the determination of 16 kinds of harmful substances(eg.methanol,volatile halohydrocarbons,benzene homologues,the free toluene diisocyanate and hexane diisocyanate)in solvent based coatings.The extraction and separation efficiencies of targeted compounds by using organic solutions of ethyl acetate,n hexane,tetrahydrofuran and acetonitrile were investigated.The procedure of sample pre treatment and the conditions of instruments were optimized.The quantitative analysis of compounds were carried out by using 2-bromopropane and 1,2,4-trichlorobenzene as the internal standard,and acetonitrile as extraction reagent.The result indicated that the calibration curves of the 16 harmful substances were linear in the range of 5-200 mg/L with correlation coefficients no less than 0.999.The spiked recoveries ranged from 80% to 105% with relative standard deviations less than 5.0%.The detection limits ranged from 0.08 mg/L to 1.41 mg/L.The method was rapid,sensitive and accurate.