In order to understand the regulation mechanism of 17β-HSDs on gonadal development and reproductive endocrine of mollusks, this paper has reviewed the types and functions of 17β-HSDs, classified all the subtypes reported so far, and summarized the cloning, expression, function and mechanism of 17β-HSDs in mollusks. In spite of some progress made in 17β-HSDs regulating the reproductive process of mollusks, many underlying problems remain unsolved and further investigations are needed: ① discovering new subtypes of 17β-HSDs in mollusks; ② analyzing the temporal and spatial characteristics of expression; ③ investigating the structure-activity relationship; ④ clarifying the impact of environmental pollutants and making the corresponding countermeasures; ⑤ guiding the practice and application of aquaculture industry. This review has referred to former research on other species, which offers reference and guidance for further study on the mechanism and application of 17β-HSDs in regulating gonadal development and reproductive endocrine of mollusks.