The invention belongs to the field of 
plant chemistry, in particular to a method for extracting active molecule 
alkaloid of 
paper mulberry and application of the 
alkaloid. The method comprises the following steps: taking roots or / and 
bark or / and leaves as raw materials, and extracting the raw materials with water or water-containing alcoholic solution at normal temperature or 
heating temperature; making the extracting solution pass strong acid type or weak acid type cation exchange resin, and adsorbing the 
active components of the extracting solution on the resin; washing a resin column with water, eluting the resin column with 
ammonia water / alcoholic solution, and concentrating and 
drying the eluent to obtain the total 
alkaloid of 
paper mulberry; and concentrating the extracting solution, extracting the concentration solution with 
ethyl acetate, alkalifying the water phase with alkali until the pH value is 12, extracting the water phase with n-butyl 
alcohol, and concentrating the extracting solution of n-butyl 
alcohol to obtain the total alkaloid of 
paper mulberry. The alkaloid of paper mulberry prepared by the method can be directly used or added with edible auxiliary materials to prepare a medicament or 
functional food capable of preventing diabetes and complications of the diabetes, or preventing 
obesity, or treating viral influenza. The method also has the advantages of simple process, low cost and easy industrialization.