A biological control programme against Pieris rapae L. (Lepidoptera, Pieridae) in China made release of Cotesia rubecula (Marshall) imported from Canada in 19791980. A native species Cotesia sp. which is solitary endoparasitoids of Pieris rapae in Beijing has been misidentify to C.rubecula by Hu et al. since 1981. We further examined specimens of Cotesia sp. and C. rubecula. We recognize that C. rubecula and Cotesia sp. are difference species, and the both species are very similar. But there is a large discrepancy in the structure of stigma of fore wing, submarginal cell of hind wing, the morphological characters of digitus (form, teeth numbers) and parameral plate (form) of male genitalia. In this paper the specimens which were collected from Beijing were identified as Cotesia sp. (nr. rubecula Marshall) by authors.