In this research, the histology of Flat crab's ovary {Ocypode saratan) is assessed in Chabahar Bay of Oman Sea during the period of December 2005 to December 2006. Ten ovaries of such species were sampled and fixed in the bouin solution. The samples were undergone the histology, preparation, dehydration, clearing and paraffmation according to standard procedure. Then sections of 5 μ were prepared and after coloration, they were studied under an electronic microscope. Gonad maturity stages of such species were determined in 6 microscopic levels. In first and second stages, the crab is immature and third to sixth stages, the crab is mature. Oocyte diameter sizes in ovary through ovulation process are: Immature (<20 μrn), rudimentary (20-40 μrn), developing (40-70 μrn), intermediate (70-90 μrn), advanced (90-160 μrn) and resting (>160 μrn). Maximum dimension of oocyte frequency is 152.3±0.5 micron. Salinity has complementary effect on temperature and increase in salinity results in complete maturity of gonads. Female sex has almost during May and September. The peak has been registered in May 4.12.