The freshwater clam (Corbicula fluminea Muller) is one of theimportant aquatic products in Dian Shan Lake. The age(length)of maturation,repro-ductive cycle and breeding season of the clam were studied in this paper. The breeding season of the clam is from June to September, and some of themcontinue to breed until the end of October.The optimum water temperature for breed-ing is from 25°-28℃. Each individual could ovulate more than once. The age(Iength)of maturation is about 12-13 mm. Since the length of individuals increases, thevolume of the follicles, the age and sperms also increase in size and quantity. For theconservation of the resource, the best season for catch will be October so that thepopulation will maintain in a high level.