Abstract: The embryonic and postembryonic development of the Cladoceran Moina affinis at 30℃ and 20℃ has been studied in the laboratory.The duration of embryonic and postembryonic development is inversely proportional to the temperature. Embryonic development lasts 18—20 hrs at 30℃ and 42—48 hrs at 20℃. The total life span is 15.7 days at 30℃ and 33.3 days at 20℃.There are only two pre-adult instars followed by thirteen adult instars at 30℃ whereas at 20℃ there are three pre-adult instars followed by twelve adult instars.The rate of egg production on a cumulative basis varies with temperature. It is found that at 30℃ Moina affinis has a higher rate of egg production (a=1.1811) than at 20℃ (a=0.9643)The data on the life cycle of Moina affinis has been compared with other five cladoceran species.