Abstract: An analytical method for determination of 2-aminoacetophenone in different Syrup by online SPE and HPLC MS/MS was developed which online SPE could enrich the target and remove the interference and HPLC-MS/MS could determine and quantitate of 2-aminoacetophenone. The SPE column was Acclaim PA (4.0mm×30mm) , and the analytic column was ODS (2.1mm×150mm, 3.0μm) , and the Mass Spectrometry's parameters ( S-lens, CE, etc.) were automatic optimization with SRM mode. The results showed that the calibration formula was Y=-12123.6+33480.1X, the correction coefficient was above 0.9999, and the calibration curve was linear in the range of 0.3 ¹50ng/mL, injection volume was 10.0μL and the detection limit of the method (with S/N=3) was 0.03ng/mL, the recoveries of spiked samples were more than 93%. Then 3 different samples were analyzed with this method, the contents were not detected.