Abstract: This paper reports the results of investigations on biomass and production of 5 species of Cyclopids, 5 species of Calanoids at the two sampling stations in Lake Donghu, Wuhan, during 1980—1982. The total annual average biomass of Copepoda was 321.74 mg dry wt. m-2, among which Cyclopoida was 194.7 mg dry wt. m-2 and Calanoida was 127.04 mg dry wt. m-2, being 60.51% and 39.49% of the total, respectively. The total annual production for Copepoda was 16.959 g dry wt. m-2, among which Cyclopoida was 11.225 g dry wt. m-2, and Calanoida was 5.734 g dry wt. m-2, contributing 66.19% and 33.81% to the total respectively. the annual P/B ratio of Copepoda was relatively high, reaching 52.55.M. leuckarti ranked first in the biomass and production, being 31.71% of the total annual average biomass and 49.82% of the total annual production for Copepoda, and it was followed by S. forbesi, C. vicinus vicinus and N. incongruens in turn. The proportion of the total production contributed by the various development stages was also determined, and nauplius was found to be more important, on average,.contributing 45.65% of the total.