Prosopocoilus gracilis (Saunders, 1854) and its seven allied species from China are revised. Lectotype, paralectotypes of P. gracilis (Saunders, 1854) and P. denticulatus (Boileau, 1901) are designated. The doubtful species, P. piceipennis (Westwood, 1855) is evidently confirmed as a valid species with verification of its type depository. Two highly similar species, P. crenulidens(Fairmaire, 1895) and P. denticulatus (Boileau, 1901) are compared in detail for correcting longstanding wrong diagnoses of them. P. similis Schenk, 2009 is illustrated with male genitalia firstly. Two recently-published species, P. andreasi Schenk, 2009 and P. katsurai Fujita, 2010 are treated as new junior synonyms. All the five valid species in this paper are redescribed, with illustrations of adult (including type) habitus, male and female genitalia if they are available. A key to large males is provided for identifying them briefly.