Abstract: The testicular structure and reproductive cycle of ovoviviparous teleost,Sebastiscus marmoratus was studied in this paper.The testes of S.marmoratus are lobular type.In August and September of every year,the testes are at the stage of spermatogonic proliferation,when primary spermatogonia divide and develop into secondary spermatogonia,which and Sertoli cells form spermatogenic cysts.From October to next January,the testis enters spermatogenesis.During this stage,germ cells in the spermatogenic cysts develop into sperms gradually.February till July is the stage of sperm degeneration and absorption,when there are only primary spermatogonia and some remains of sperms.During reproductive time,sperms are transferred to urinogenital papilla via vasa efferentia and vasa deferentia,and enter the female reproductive tracts by the way of internal fertilization.