Acrylonitrile－Butadiene－Styrene（ABS）plastic is widely used in toy manufacturing industry. The chemical safety of ABS plastic toys is affected by the residual monomer without polymerization. In order to more accurately evaluate the chemical safety of ABS plastic toys and better protect children's health and safety， a rapid， accurate and sensitive method for the determination of acrylonitrile and styrene residues and migration in ABS plastic toys was established， based on the headspace－gas chromatography－mass spectrometric（HS－GC－MS）technique. Firstly， the headspace equilibrium temperature and equilibrium time of the residue determination method were optimized. Results showed that the optimal equilibrium temperature was 110 ℃ and the optimal equilibrium time was 15 min. Then， the headspace equilibrium temperature， equilibrium time， sampling volume and salting out conditions were optimized by using simulated sweat and simulated saliva as the migration medium. The results showed that the optimal conditions were as follows： equilibrium temperature 70 ℃， equilibrium time 30 min， sampling volume 10 mL and the salt amount 3.5 g. The limits of quantitation（LOQs）for determination of residual acrylonitrile and styrene were 0.4 mg/kg and 1.0 mg/kg， respectively. The correlation coefficients（,r,2,）were greater than 0.999 8 in the linear range of 0.4－2 000 mg/kg. The recoveries were in the range of 93.0%－108% with relative standard deviations（RSDs）not more than 7.2%， while the LOQs for determination of acrylonitrile and styrene in the migration solution were 1.0 μg/L and 0.05 μg/L， respectively. The correlation coefficients（,r,2,）were not less than 0.998 1 in the linear range of 0.05－100 μg/L. The recoveries ranged from 88.4% to 104%， with RSDs not more than 9.5%. Finally， the method was applied to the determination of acrylonitrile and styrene monomer residues and migration in 38 ABS plastic toys. Styrene was detected in all 38 ABS toy samples， and acrylonitrile was not detected in only one of them. The residual amounts of acrylonitrile and styrene were in the ranges of 4.02－58.25 mg/kg and 1.49－1 840.19 mg/kg， respectively. The migration amounts of acrylonitrile in simulated sweat and simulated saliva for 60 min were 0.09－0.58 mg/kg and 0.11－0.67 mg/kg， while those of styrene in simulated sweat and simulated saliva were 0.11－0.88 mg/kg and 0.12－0.92 mg/kg， respectively. The detection results showed that there existed a certain amount of acrylonitrile and styrene in ABS plastic toys， and these residual monomers might migrate from ABS plastic toys under certain conditions， which pose a potential hazard to children. Therefore， the content level and exposure safety of monomers in ABS plastic toys need to be further evaluated. The method is simple， rapid， sensitive and accurate， and it is suitable for the determination of acrylonitrile and styrene residues and migration in ABS plastic toys， which provides a technical support for the safety evaluation on ABS plastic toys.