The invention relates to the technical fields of 
medicine, food and health products, and discloses a highly efficient preparation method of antitumor 
drug sodium cantharidinate.  Add 
cantharidin essence into 
sodium hydroxide aqueous solution, heat to dissolve, add 
activated carbon to 
reflux for decolorization for 0.5-1 hour, heat filter, wash with water, concentrate under reduced pressure, add 
ethanol, cool to 
room temperature, precipitate 
solid and dry to obtain 
white powder.  Wherein the equivalent ratio of 
cantharidin fines and 
sodium hydroxide is 1:2-3, and the weight ratio of 
cantharidin and 
ethanol is 1:3-10.  The synthesis of sodium cantharidinate and the decolorization and refining of 
activated carbon are completed simultaneously, and the 
crystallization is carried out with 
ethanol-water 
system.  The invention provides a synchronous method for synthesizing sodium cantharidate and decolorizing and refining 
activated carbon, the preparation process is simpler, the reaction cycle is shortened, the application of a large amount of 
acetone and isopropanol is omitted in the reaction process, the production cost is reduced, and  The 
pollution to the environment is small, the 
quality control is simpler, the production efficiency is improved, and the industrial production is convenient.