Under the experimental conditions, the test that Macropodus chinensis (Bloch) feeds selectively on Rotifera Asplanchna priodonta, Cladocera Daphnia pulex, Copepoda. Mesocyclops sp., mosquito larvae Culex sp. and chironomid larvae Chironomus tentans Fabricms was carried out. The magnitude of food selectivity is measured with Ivlve's index and χ² value in number and biomass of food organisms. The results show that the selectivity order is:feeding on chironomid larvae and mosquito larvae first, then Cladocera and Copepoda, and finally Rotifera. While the number of these five species in aquria is doubled alternatively, the fish between 0.5 and 4.15g in weight has the identical food selectivity. M. chinensis is a promising species used in controlling the mosquito larvae population because mosquito larvae are easy to be sought by fish in natural condition. To evaluate the food selectivity more objectively, the individual number of food organisms is more suitable than biomass; and Ivlve's index and chi-squared test used simultaneously are better than used separately.