The histology of gonadal development of Osteoglossum bicirrhosum which is a popular ornamental fish was studied by paraffin section technique and H.E staining method.The morphological characteristics and structures of ovary at stage Ⅱ-Ⅴ and testis at stage Ⅱ-Ⅵ were described.Moreover, the development of oocyte and spermatid were also described.The results showed that four months old ovaries were in stage Ⅱ, while the oocytes were in phase Ⅱ, and the nucleus occupied the half part of the cell.Eight months to two years old ovaries were in stage Ⅲ, most of the oocytes were in phase Ⅲ and egg macular and yolk granules could be observed;two to three years old ovaries were in stage Ⅳ, with the oocytes in phase Ⅳ which had yolk substance accumulated quickly and oolemma drape appeared.The ovary in stage Ⅴ was three years or more than three years old, and the oocytes in phase Ⅴ were full of yolk granules with the drape of oolemma disappeared.The primary spermatocyte in testis could be seen at the stage Ⅱ.Eight months to two years old testes were in stage Ⅲ, while the secondary spermatocyte appeared and the seminiferous tubules took shapes, and spermatids are full of the seminiferous tubules, primary spermatocyte, secondary spermatocyte and spermatids were seen at the stage Ⅳ, while the seminiferous tubules of void appeared.The testis in stage Ⅴ was three years old and more than three years old, the spermatozoa appeared and the void of seminiferous tubules became large.The testis highly vascularized and with connective tissue increased was also observed which was in stage Ⅵ.This study will provide the basic data for the artificial reproduction of O.bicirrhosum.