Abstract: Based on outdoor surveys and suction devicebased collections in a rice field as well as adjacent weed habitat from June to September 2001 and laboratory identifications of specimens obtained from the field investigations, 67 species of parasitoids were collected and identified in the rice field, and 96 in the weed habitat. The species number of parasitoids accounted for 45.9% of the total species number of natural enemies in the rice field, and 46.6% in the weed habitat. For a comparative study of community diversity, species richness (S), ShannonWiener′s diversity index (H′), Simpson′s index of dominant centralization (C) and Pielou′s evenness (E) were calculated. The results showed that the numerical values of S, H′ and C of the parasitoids in the weed habitat were higher than those in the rice field, and the value of E was lower in the weed habitat. Temporal variation of dominant species was also different between the two habitats. In both habitats, Telenomus dignus and Anagrus sp. were dominant, but each habitat also had its unique dominant species, e.g., Monelata sp.1 and Acropiesta sp.2 were common in the rice field but not in weed habitat, while Telenomus gifuensis was only common in the weed habitat. The dominant species of the parasitoids tended to colonize the weed habitat in the seedling-transplanted stage of rice, immigrate into the field in the growing stage of rice, and emigrate from the fields to live in the weed habitat again in the mature stage of rice. This clearly indicates that the weed habitat can serve as a “species pool” of natural enemies, which provides the enemies with opportunities for natural dispersal, host alternation and refuge-seeking when there is lack of suitable food or disturbances caused by cultivation in the rice field. This is favorable for ecologicallybased integrated pest management in rice ecosystems.