A method was established to determine migration of plasticizer ATBC of PVC sealed gaskets in oily simulant. The plasticizer ATBC was ultrasonic extracted and using n-hexane as the oily simulant. Qualitative and quantitative analysis of ATBC was carried out by GC/MS. The method has a good relationship at the range of 1ml/L~200ml/L, with correlation coefficients 0.9973. In the tests of accuracy and precision, the average recovery was 95.8%~105.2%, and the relative standard deviation(RSD) was 1.03%~4.72%.This method can provide some references for studying the migration of citrate plasticizers in oily food.