The invention relates to a method for simultaneously detecting seven slimming chemical components which are illegally added to traditional Chinese medicine, health food or cosmetics. According to the method, an appropriate mobile phase and a reasonable elution gradient are adopted during liquid-phase separation, so that the slimming components needing to be detected are effectively separated within 12 min, the analysis time of a sample instrument is shortened by 88%, and the work efficiency is greatly increased. Additionally, the advantages of high separation ability of the HPLC (High Performance Liquid Chromatography) technology, high sensitivity and stronger qualitative ability of the mass spectrum and the like are combined, so screening and confirmation can be simultaneously completed during one operation. By using the method disclosed by the invention, the seven chemical components including sibutramine, fenfluramine, phenolphthalein, ephedrine, caffeine, N,N-bi-demethylation sibutramine and furosemide can be effectively separated, the inspection time can be shortened, and the slimming chemical components which are illegally added to the traditional Chinese medicine, the health food or the cosmetics can be accurately and effectively distinguished.