The method of simultaneous and rapid determination of propionic acid, sorbic acid, benzoic acid, dehydroacetic acid and their corresponding salt content in food by gas chromatography was established by liquid-liquid extraction purification, which was applicable to the detection of solid non ester kind food. The result showed that the recovery rate of propionic acid was 85.1%～91.3%, the average recovery of the other three kinds of preservatives was 95.2%～99.4%; the maximum coefficients of variation (CV, n=6) in laboratory were less than or equal to 4.7%; the detection limit of the four kinds of preservatives were all below 0.002g/kg. With the interference of impurity, they can be further confirmed by different polar capillary column. The method has the advantages of wide application range, high detection efficiency, good reproducibility, high accuracy and low detection limit, and the application is of great significance for the supervision and inspection of food safety in China.