The effects of stocking density on growth, sex differentiation and early gonadal development of M. rosenbergii were analyzed by the indexes (such as growth, survive, sex differentiation and gonadal development) at four stocking densities (7.50×10⁴, 12.75×10⁴, 42.00×10⁴ and 97.50×10⁴ ind/hm²). The result showed that:at the stocking densities from 7.50×10⁴ to 97.50×10⁴ ind/hm², the growth, specification uniformity, sex differentiation and gonadal development of M. rosenbergii were significantly influenced by stocking density. With the time prolonged, the greater growth inhibitory effects from stocking density appeared. The ratio of body weight gain acceleration of M. rosenbergii in groups of 7.50×10⁴ ind/hm² to 97.50×10⁴ ind/hm² increased from 2.3 at 10 d to 3.4 at 80 d; the sex differentiation and gonadal development time of low stocking density groups is about 10d earlier than that of the high stocking density group, but the sex differentiation and gonadal development specification of low stocking densities is greater than that of the high stocking densities. The initial average body length of female M. rosenbergii in group of 7.50×10⁴ ind/hm² (4.158±0.592) cm is 1.09 cm longer than that in group of 97.50×10⁴ ind/hm²; sex ratio was not influenced by stocking density, but the survival rate of female M.rosenbergii was significantly influenced. The external morphology scale and age were delayed by the influence of stocking density. The result showed that the growth and gonadal development were significantly influenced by stocking densities. Suitable stocking density is an effective measure to prevent the precocity of M. rosenbergii. These results may provide a basis for the breeding production and genetic breeding of M. rosenbergii.