Abstract: The sample of PVC plastic toys (1.00 g, to be cut up previously) was extracted in a microwave extractor with ethylacetate (10 mL) for 50 min at 90℃. The extract was evaporated to 5 mL, and perfluorooctane sulfonates (PFOS) in it were extracted by MSPD extraction using PFOS-MIP (3 g) as adsorbent. PFOS adsorbed on the MIP were eluted with methanol (5 mL). The eluate was derivatized by reaction with 400 μL of TBAH solution (10%, φ) for 60 min at 60℃, to give butyl perfluorooctane sulfonate with better volatility. n-Hexane was added to the solution to make its volume to 1 mL, and used for GC-MS determination under the prescribed conditions. The time, temperature and amount of TBAH solution for the derivatization were tested and studied by applying the response surface analysis, and optimum conditions were determined. It was found that linear relationship was kept between mass concentration of PFOS in the range of 1-200 μg·L^-1 and values of respective peak area. Detection limit (3S/N) of the method was 0.95 μg·L^-1. Recovery was tested by standard addition method, giving values of recovery ranged from 89.6% to 95.2%. Values of RSDs (n=10) found were in the range of 6.4%-8.3%.