Cordyceps militaris is a medicinal fungus used in traditional Chinese medicine that has healing properties but degenerates quickly when repeatedly cultured in laboratories. This research found that the loss of genetic mating-type information during subculturing is the main cause of this degeneration. By separately culturing different genetic types and mixing them before production, or by using stable single genetic-type strains, farmers can maintain consistent quality fruiting bodies for harvest and medicinal use.