During March to May of 2005, mature female swimming crabs were held in captive conditions and fed with fresh clam, Sinonovacula constricta
. The spawned crabs were sampled and dissected to investigate the changes to the gonadosomatic index (GSI), hepatosomatic index (HSI), external features of ovary, ovarian histology and its stages during the second ovarian development of Portunus trituberculatus
. The results demonstrated that: (1) the process of the second ovarian development could be divided into four stages: stage I ovary was ribbonlike and milk white or buff, the main cells in the ovary were endogenous vitellogenic oocytes (EN) and previtellogenic oocytes (PR); stage II ovary was buff and orange, the main cells were exogenous vitellogenic oocytes(EX); stage III ovary was deep orange, the main cell types were ex and nearly-mature oocytes (NO); stage IV ovary was ripe, the main cell type was mature oocytes(MO); (2) During the period, the GSI increased significantly, while the HSI did not show a significant difference. A positive correlation could be found between GSI and ovarian development, days after spawning, however there was no significant correlation between GSI and HSI.