The invention relates to a preparation method of an
isodon excisoides total diterpenoid extractive, which is capable of effectively solving the problem of extracting total diterpenoid from
isodon excisoides with high quality and high extraction rate. The preparation method disclosed by the invention comprises the following steps of crushing
isodon excisoides, decocting by adding water, filtering water decoction, and cooling to form sampling solution; after immersing macroreticular resin by using
ethanol, dynamically cleaning resin by using
ethanol, washing till
alcohol smell does not exist, immersing by using
hydrochloric acid, washing again till the macroreticular resin is neutral, then, immersing by using NaOH solution, dynamically cleaning resin, washing till the macroreticular resin is neutral, after dynamically eluting
ethanol, packing the macroreticular resin in a column through a wet method, and dynamically absorbing the sampling solution through a resin column; and eluting the sample column by using water after absorbing, eluting through ethanol again, collecting ethanol eluent, decompressing and recycling the
solvent, and evaporating, thereby obtaining the isodon excisoides total diterpenoid extractive. The preparation method disclosed by the invention is simple, easy to operate and use, steady, reliable, high in product yield, good in quality, simple, practical and free from
pollution; research basis is provided for researching
isodon amethystoides diterpenoid anti-tumour candidate drugs.