Heavy metals resulted from the increase of human industrial activity are introduced into the environment through rainfall and wastewater, and have harmful effects on inhabitants. In this study, we investigated biological responses such as survival rate, growth rate, emergence rate and sex ratio, and morphological effects of mentum deformity in Chironomus plumosus, an indicator organism to evaluate pollutions on aquatic ecosystem. The survival rate of C. plumosus showed time- and dose-dependent decrease after chromium and copper exposures. Growth rate decreased at 4th day after chromium exposure and significantly reduced at exposure to relatively high concentration (copper 1000 mg L-1) for all exposure times. In addition, we observed that the emergence rate by exposure to copper 1000 mg L-1 was significantly lower than that of the control group. The imbalance of sex ratios showed at relatively low concentrations (chromium 10 and 50 mg L-1) with the high proportion of female and at the relative high concentration (copper 1000 mg L-1) with the high proportion of male. Furthermore, the morphological mentum deformities of C. plumosus observed in the exposed group according to chromium and copper exposure. These results suggest that the heavy metal exposure in environment may influence biosynthetic and morphological stresses of benthic invertebrate C. plumosus, and aquatic midge C. plumosus are potential indicators for toxicity assessment of heavy metals such as chromium and copper.