Effective methods for induction of diploid gynogenesis of the summer flounder Paralichthys dentatus are needed to initiate monosex culture, which will allow farmers to take advantage of the more rapid growth and larger size attained by females and will maximize profit potential for the culture of this species.To induce diploid gynogenesis in summer flounder, eggs were fertilized with heterogenous cryopreservative sperm of Lateolabrax japonicas, which was irradiated with UV ray to be genetically inactivated, and cold shock was used to prevent extrusion of the second polar body. Results indicated that, just like the homologous sperm of summer flounder, the cryopreservative sperm of Lateolabrax japonicas could induce diploid gynogenesis of summer flounder. Diploid gynogenesis was induced by activating egg development with UV irradiated sperm (80 mJ/cm², the homologous or the heterogenous sperm) for 5 min in seawater at 18 ℃, and then subjecting the eggs to cold shock in 3 ℃ seawater for 45 min. And the dipoid gynogenesis induction rates of the homologous sperm and the heterogenous sperm were 32.66%±7.03% and 28.00%±6.48%, respectively. It was certified that the larvae were gynogenetic diploid by morphology, flow cytometry and microsatellite DNA analysis. It is the first time to report effective methods for induction diploid gynogenesis of the summer flounder by heterogenous cryopreservative sperm of Lateolabrax japonicas, which provides technological measures for sex control and genetic improvement of summer flounder.