Abstract: The China fir borer, Semanotus bifasciatus sinoauster Gressitt has been treated as a subspecies of the juniper borer, Semanotus bifasciatus bifasciatus Motschulsky since 1951. During 70' s a great deal of works were done in combat with these borers in twelve provinces of China. All faetsrevealed that the southern subspecies differes from the nominate subspecies in host preference, the former is injurious to China fir while the latter to juniper, and the juniper log trap is effective to the latter subspecies, but not to the former subspecies. The geographical distribution is different, the former is predominant in south China, while the latter in north China, but there is a wide overlapping district in eastern to southwestern China. In addition, cross hybridization test between the two synpatric populations showed hybrid incapatibility and sterility.The authors performed a series of comparative study on the external morphology and on the anatomy of male genitalia and female ovipositor and speratheca. The detailed descriptions and measurements showed significant distinctions between these two kinds of borers. The authors suggest that they should be two different species, the taxonomic position of the China fir borer should be raised to species rank, and the scientific name should be revised to Semanotus sinoauster (Gressitt).