The gonadal development of Chinese mitten2handed crab ( Eriocheir sinensis) is correlative with the Ca2 + level in the hemolymph. For the one autumn Chinese mitten2handed crab (so called buttony crab) , the hemolymph Ca2 level of the precocious female buttony crab is much higher than that of the normal female buttony crab (21. 25 ±11. 89 mmol ·L -1 for the former and 13. 70 ±1. 17 mmol ·L -1 for the latter) . On the contrary , the hemolymph Ca2 level of the precocious male buttony crab is only 16. 33 ±1. 38 mmol·L -1, which is lower than that of 20. 13 ±2. 37mmol ·L -1 of the normal male buttony crab. The Ca2 level in the hemolymph of male adult crab (two autumn crab) is almost the same as that of the male precocious buttony crab. With the growing and maturating , the hemolymph 17β2estradiol (17β2E2) concentration of the female crab rises gradually , 0. 15 ±0. 05ng·ml -1 for the normal female buttony crab , 0. 59 ±0. 15ng·ml -1 for the precocious female buttony crab and 2. 31 ±1. 08ng·ml -1 for the female adult crab (two autumn crab) , respectively.