The invention discloses a preparation method of 
griseofulvin. The preparation method comprises the following steps of: A, heating 
griseofulvin fermentation liquor, adding 
calcium oxide to adjust the PH, carrying out 
solid-liquid separation by using a sheet frame, adding 
calcium oxide to a 
filter cake to granulate, and extracting by using 
acetone to obtain a 
griseofulvin acetone extracting solution; B, decoloring the griseofulvin 
acetone extracting solution by using an 
active carbon column to obtain a griseofulvin decoloring solution, feeding the decoloring solution into a concentration tank, and crystallizing by concentrating to obtain wet griseofulvin crystals; and C, washing the wet griseofulvin crystals once by using a 
dichloromethane and 
ethanol mixed solution while stirring, then washing the wet griseofulvin crystals once by using medicinal 
ethanol with the concentration of 95 percent while stirring, 
drying the crystals by using a vacuum drier, and carrying out 
superfine grinding on the dried crystals to obtain the griseofulvin product. Compared with a traditional preparation method, the preparation method disclosed by the invention has the advantages that the 
crystallization times in the process of preparing the griseofulvin in the prior art is reduced, the yield loss caused by recrystalization of griseofulvin is effectively avoided, the total yield of the griseofulvin is improved by 7-10 percent, and the production cost is greatly reduced.