The invention relates to the technical field of medicine residue detection. An objective is to provide a method for fast detecting the residual quantity of 34 illegally-added medicines in a weight-losing health food. The method is fast and accurate, and is high in sensitivity and wide in application range. According to the technical scheme, the method comprises: 1) preparing a self-made extractedliquid, which comprises refluxing a mixture of methanol, acetone and octanol polyoxyethylene ether at 60-65 DEG C for 30 min and performing cooling for later use; 2) taking health product tablets, capsules or particles, performing pulverization, accurately weighing 3-10 g of the sample, putting the sample in a centrifuge tube provided with a plug, adding 20-60 mL of a self-made extracted liquid, performing mixing in a vortex oscillator, performing supersonic wave extraction for 2-10 min, performing centrifugation, taking 1 mL of the supernatant out, blow-drying the supernatant, and redissolving the obtained product with 2 mL of 50% of an acetonitrile aqueous solution; and 3) filtering the redissolved solution via a filter membrane with the micropore size being 0.22 mum, and measuring the filtrate via HPLC-MS/MS (that is high performance liquid chromatography and mass spectrum and secondary mass spectrum).