Tench,Tinca tinca is one of the important economic fishes and a new species of fish of farming and stocking in inland waters in Beitun area,Xinjiang.The annual histological changes in ovary of tench were investigated.The result showed that the age of maturity of tench was 3-4-years old in Beitun area.The spawning season was from the last ten-day of May to July.In this period,the mature coefficient of ovaries was 11.50%-12.25%, with an average of 11.88%.The oogenesis was composed of five consequent phases.After spawning,few mature oocytes were re-absorbed subsequently in ovary and the ovary soon degenerated into stage II and remained in this stage from November to Match next year and began to develop again in the next April.According to the histology of oocytes and investigation of field works,tench should be classified into batch-spawing fish.