Objective: to separate and extract the active ingredient(s) which can produce the function of decrease the blood sugar from TCM litchi nuclear, and to study the chemical compound(s) of the effective parts. Method: using animal experiments andα-glucosidase inhibitors to select the active ingredient(s) extracted from litchi nuclear. Use the method of phenolic acid to study the chemical property of the active ingredient(s). The repeated Silica gel column chromatography and Sephadex LH-20 etc. methods were used...