The invention relates to a preparation method of high-purity salvia miltiorrhiza, which comprises superfine grinding of salvia miltiorrhiza medicinal material, soaking and extracting in ethyl acetate, soaking and extracting medicinal dregs in water, absorbing the extract by AB-8 resin, eluting and eluting After the solution is concentrated, adjust the pH to 7-8, heat at 110°C-130°C for 30 minutes, filter, adjust the pH of the filtrate to 1-3, let stand, precipitate, filter, the filtrate is adsorbed by AB-8 resin under acidic conditions, and eluted with pure water , the eluate was adjusted to a pH value of 7-8, concentrated and dried to obtain a solid Danshensu sodium, which was recrystallized from methanol to obtain a high-purity Danshensu sodium.