Pretreatment for bisphenol A (BPA) in plastic bottled lactic acid drinks was discussed and a method for the determination of BPA by liquid chromatography-tandem mass spectrometry(LC-MS/MS)was established.Methods Samples were protein precipitated under alkaline condition before solid phase extraction. The elution was separated by column with water and methanol as the mobile phase(volume ratio 40∶60). LC-MS/MS ion electrospray ionization mode(ESI-)was adopted together with multiple reaction monitoring (MRM) and external standard quantitative analysis. Results The method had good linearity within 2.0 to 100.0 μg/L; The instrumental detection limit was 0.01 ng; The method detection limit was 0.001 μg/kg with the sample mass of 10 g; Recoveries of Bisphenol A of high, medium or low concentration (80、50、10 μg/L) were 100.9%-107.5%. The coefficients of variation were 6.2%-7.6%.Conclusion This method is suitable for the determination of trace amounts of BPA in plastic bottled lactic acid drinks with high sensitivity, simple pre-treatment, batch testing, and high-speed.