Cordyceps, an entomopathogenic mushroom, is a famous traditional Chinese medicinal herb (TCM). This higher fungus contains various known and untapped bioactive metabolites, and is looked at as an important source of natural drugs while simultaneously provides good opportunities for discovering new drugs with immunomodulatory, antitumor, hypoglycemic and hypocholesterolemic functions. Therefore, the Cordyceps spp. has been receiving an increasing interest around the world as an interesting natural drug resource. Various secondary metabolites from Cordyceps fungi were reported to have antitumor activities, and antitumor mechanism of those bioactive compounds possesses multi-target, multi-level and multi-pathway characteristics. Challenges in investigations on Cordyceps fungi include the further elucidation of antitumor molecular mechanism and relationship between structure and function of their secondary metabolites.