These experiments were conducted to investigate the biological characteristics of Cotesia plutellae (Kurdjumov), a larval parasitoid of plutellae xylostella L. At four constant temperatures of 18, 20, 25, and 3$0^{circ}C$, the developmental periods from egg to adult emergence of C. plutellae were 29.52, 26.19, 14.17, and 10.35 days, respectively. Developmental threshold temperatures and effective temperatures were 12.3$^{circ}C$ and 117.7 degree-days in egg-larval stage, 12.4$^{circ}C$ and 64.7 degree-days in pupal stage. The average longevities of female adults were 16.93, 14.83, 13.7, and 7.87 days, and the average numbers of eggs laid per female were 10.9, 17.7, 31.8, 30.3 at the respective temperatures, respectively. The intrinsic rates of increase were 0.047, 0.075, 0.132, and 0.199 while the population doubling times were 14.7, 9.2, 5.3, and 3.6 days at 18, 20, 25, and 3$0^{circ}C$, respectively. The average parasitisms of C. plutellae in the conventional spray field were 14.9% and 9.8% in spring and autumn of 1996, respectively. The surveyed parasitoids of p. xylostella were 4 species including C. plutellae (Kurdjumov), Diadsgmo sp, Diadromus sp, and Oomyzus sokolowskii (Kurdjumov).