Objective To develop a method to detect benzoic，sorbic acid in high-fat foods like oily bean curd by capillary gas chromatography．Methods The samples were eliminated matrix interference by NaOH-ZnSO4，extracted by ultrasonic extraction，then filtered，centrifuged，acidized，extracted by ether，evaporated to dry，fixed using anhydrous ethanol and finally determined by capillary gas chromatography． Results The linear range was 0-300μg/ml (r＞0.9990). the lowest detecting limits of sorbic，benzoic acid were 1mg/kg．The relative standard deviation was 1.07-3.14%， The recovery was 90.6-101.8%．Conclusion This method is simple，rapid accurate and reliable to detect the benzoic，sorbic acid of high-fat foods like oily bean curd．