Oncorhynchus mykiss is an economical cold water fish with high nutritional value. The study on the ovary development and correlative coefficients could provide the basal data for breeding and production of rainbow trout (Oncorhynchus mykiss).Using anatomical, histological methods, this article studied the ovary of 4~33 months old fishes and annual change in the ovary of mature Oncorhynchus mykiss, divided stages of ovary development, divided phases of the oocytes. At the same time, this article recorded dat...