To establish a thin layer chromatography (TLC) combined with Raman spectroscopy method and detect four chemical components (theophylline, caffeine, nandrolone phenylpropionate, spironolactone) added illegally in the slimming health food. The doping ingredient and substrate were separated with TLC, viewed and located with UV light (254 nm), the spot of the doping ingredient is concentrated on the TLC plate before detecting the Raman spectroscopy of the concentrated point directly with 780 nm laser source. The effects of different formulations of slimming health food were studied, the limit of detect (LOD) was validated, and the TLC Situ Raman Spectroscopy method was established initially for detecting four chemical components added in the slimming health food. The common substrate in the slimming health food had no interference with the detecting results of doping components. The LOD was 2~4 μg. Two out of nine kinds of health food were detected to be with caffeine. In this study, we established TLC and Raman spectroscopy for the first time which was used for quick identification of four kinds of illegal chemicals added in health food, such as theophylline, etc. The method is precise, sensitive, rapid and simple, which could provide a new reference for the technology research of rapid detection of the ingredients added illegally in health food.