Monthly investigatiom were made on the population of Chinese freshwater crab, Sinopotamon yangteskiense Bott, 1967 from April, 1984 to Match, 1985. The data on 4413 specimens show that the growth was affected mainly by temperature. During the April to November growth period, the crabs’ major development occured from June through October. One year was required for a fine white oocyte to develop into a mature egg. The reproduction period was June-October. Females bearing eggs were taken from June-August, and crabs with young were found from July-October. The females reproduced once a year but could for more than one year. The number of eggs carried by a female varied greatly according to the size of the crab, ranging from 30 to 100 eggs. New-bom crabs become mature after 1-2 yeats. The sex ratio was approximately 1:1 in the overall population. However, the larger crabs are predominantly male. The age distribution of S. yangtsekinese was estimated from size frequency histograms. There were more adult crabs Monthly investigatiom were made on the population of Chinese freshwater crab, Sinopotamon yangteskiense Bott, 1967 from April, 1984 to Match, 1985. The data on 4413 specimens show that the growth was affected mainly by temperature. During the April to November growth period, the One year was required for a fine white oocyte to develop into a mature egg. The sale period was June-October. Females bearing eggs were taken from June-August, and crabs with young were found The number of eggs carried by a female was greatly varied according to the size of the crab, ranging from 30 to 100 eggs. New-bom crabs become mature After 1-2 yeats. The sex ratio was approximately 1: 1 in the overall population. However, the larger crabs are predominantly male. The age distribution of S. yangtsekinese was estimated from size frequency histograms. There wer e more adult crabs