Abstract: To provide reference for seed breeding of guppy (Poecilia reticulata), we investigated the histology of its female reproductive system and oogenesis process by light microscopy. Resultsindicate that the female reproductive system of guppywas made up of ovary, ovum delivery ducts and cloaca. Oogenesis process of guppyexperienced6 stages: At Stage Ⅰ, oocytes were mainly composed of oogonia. At Stage Ⅱ, primary oocytes reached small growth stage with growth loop, yolk nucleus and one layer of follicular membrane. At Stage Ⅲ, primary oocytesforming2 layers of follicular membranes and egg envelopesreached great growth stage, and yolk granules began to accumulate. At Stage Ⅳ, primary oocytes reached late phase with cell polarization and completely developed egg envelopes. At Stage Ⅴ, oocytes matured and yolk granules condensed, vitelline foam almost distributing in the inner edge of cell membrane and follicular membrane shrivelling. At Stage Ⅵ,atretic follicles weredigested and absorbed into connective tissue by follicular cells.