Abstract: Interspecific competition among three parasitoids of Bactrocera dorsalis (Hendel) larvae, Diachasmimorpha longicaudata (Ashmead), Psyttalia incisi (Silvestri) and Fopius vandenboschi (Fullaway), was investigated at 26 ℃ in the laboratory. Results showed that parasitism rates per female D. longicaudata were 13.5% and 13.1%, significantly higher than those by P. incisi and F. vandenboschi, respectively, when the former was combined with each of the latter two at the same numbers. When twice number of P. incisi or F. vandenboschi was combined together with D. longicaudata, the parasitism rates per female D. longicaudata were 19.7% and 18.4%, respectively, while those of P. incisi and F. vandenboschi were 11.3% and 9.7%, respectively. When D. longicaudata was combined together with P. incisi or F. vandenboschi at a ratio of 2:1, the parasitism rates per female D. longicaudata were 19.4%, and the parasitism rates of P. incisi and F. vandenboschi were 7.6% and 8.8%, respectively. The results show that D. longicaudata has stronger competitive ability than the other two parasitoids species.