Abstract: The effects on embryonic development of the Chinese mitten-handed (Eriocheir sinensis) ar water temperature which included six sets of 15℃,18℃,23℃,26℃,29℃ and ambient temperature were studied by light microscopic from December,1987 to May,1988.The results showed briefly in the following:1.The water temperature ranges from 9.6±3.6℃ to 23℃ were suitable for embryonic development of the Chinese mitten-handed crab,beyound this water temperature ranges,it would be dangerous or lethal to the crabs.2.The optimum water temperature for embryonic development of the Chinese mitten-handed crab was 18-23℃.3.The early development of the embryo was quite sensitive to water temperature,the higher water temperature was,the less time embryonic development spent,but embryonic concordant rate was gradually decreased.4.Alternating water temperature was found out to benefit for embryonic development of the crab.