A high-performance liquid chromatograph-mass spectrometric(LC-MS/MS) method was proposed for the determination of thirty chemical compositions,which were illegally mixed into the antiobesity traditional Chinese medicine and health products.The conditions of extraction and mass parameters were optimized.The drugs were extracted with methonal in ultrasonic condition,separated on a C18 chromatographic column using a mixture of acetonitrile and water(containing 10mmol/L ammonium formate,0.1% formic acid，10% methanol) as mobile phase.The detection of analytes was performed by positive-ion and negative-ion electrospray ionization mass spectrometry(ESI-MS) under multiple reaction monitoring(MRM) mode.The method was proved to be able of covering large area,simple,rapid,accurate and reliable.It was used in screening and examination of illegally added chemicals in Chinese traditional medicine and health food.