AIM:To analyze the dissolved content of main constituents of Maxing Shigan Decoction(Herba Ephedrae,Semen Armeniacae amarum,Gypsum Fibrosum,etc.) and powder applied in experiment.The experiment was carried out simulantly in vitro;i.e.drug passed through metabolically man-made stomach liquid and stomach-intestine liquid. METHODS:The experiment of decoction and its powder of Maxing Shigan Decoction were carried out respectively.main ingredients of component drugs in compound Maxing Shigan Decoction were chosen to analyze the dissolved content by the aid of GC and Complexometry. RESULTS:There was a distinctive difference in dissolved content of main ingredients. CONCLUSION:The law of dissolved content change provides a quick and efficient scientific basis for clinical dosage and determination of quality standard.