The structure of reproductive system in Octopus variabilis was studied by anatomical,histological and histochemical methods.O.variabilis is diecious and antigeny.The third right arm of male O.variabilis is hectocotylized. The female reproductive system of O.variabilis is composed of one ovary,a pair of oviducts and oviducal glands.Sexual cord from the ovarian wall is linear and branched with many follicles connected to egg pedicle.Each follicle is made up of one oocyte surrounded by monolayer follicular cells.Oviduct exhibits abundant longitudinal ridges and its epithelial lining is simple ciliated columnar epithelium.The glandular epithelium of oviducal gland is formed by two types of cells: gland cells Ⅰ are bigger and their nuclei are circinal and big also; gland cells Ⅱ are irregular and their nuclei are spindly and anachromasis.The male reproductive system of O.variabilis contains spermary,front deferent duct,sperm capsule,accessory gonad,blind sac,back deferent duct and spermatophore.The spermary is divided into many foliolia by connective tissue.The spermatogenetic cells from the wall of foliolum transform into spermatozoa in the foliolar cavity gradually.The front deferent duct,blind sac and accessory gonad can also secret much mucosubstances to form spermatophore.There are many longitudinal ridges in the sperm capsule and the back deferent duct.The cilia distributing on the free end of the back deferent duct epithelium play an important role in transporting germ cells.The main function of the spermatophore sac is to stockpile the spermatophore.The smooth muscle of the spermatophore sac wall can help to release the spermatophore at the time of copulation.