Pagrus major), followed by hydrostatic pressure treatment to block the first mitotic division. The initiation time, duration time and pressure value of hydrostatic pressure were optimized in this study. The results showed that the treatment with hydrostatic pressure (650 kg/cm²) for 6 min starting 60 min after fertilization was the optimal parameters combination. Under this condition the fertilization rate and hatching rate at this scenario were 67.80% and 54.23%, respectively, which were significantly higher than that of all the other treatment groups(<0.05). The embryo not treated by hydrostatic pressure (haploid) were identified via flow cytometer, and its relative DNA content was about half that of normal diploid. The mitotic gynogenetic embryo had the same DNA relative content with normal diploid. The analysis results showed that mitotic gynogenetic diploids could be successfully prepared.