Based on the frequent sampling (15 times) from June, 1987 to May, 1988 and larvae culture in laboratory, the biological characteristics and annual population variance of three chironomid species from South Lake (Wuhan), China were studied. Tanypus chininsis Wang:living in no nest, feeding on detritus and algae, overwintering in only 4th instar, and having an emergence period from August to September and one generation a year. The maxiumum density (848 ind./m²) and biomass (2.28g/m²) occur in September. Tokunagayusurika sexpapilotms (Yan & Ye):nesting vertically, feeding on detritus, overwintering in 1~4th instars, and having a long emergence period from November to January and a generation yearly, different from that in the other area of China. This species has a particularly vertical movement, i. e. moving downward (more than 20cm) from May to October and upward in other months. Therefore, it may be used as a heat indicator. Chrronomus plumosus f. semireducius Lenz:nesting in "U" shape, feeding on detritus, overwintering mainly in 4th instar, having two emergence peaks in May and August seperately, reaching its maximum density (1508 ind./m²) and biomass (9.9 g/m²) in September and October respectively, and moving downwards in winter. In addition, the regressive equations of the length-weight relationship of the three species were given.