Crab is one of the important commercial crustaceans and plays an important role in the marine ecological system as well. Its exploitation and utilization have been recognized in the world. In this paper, the current studies about the fecundity and ovary development of crab have been discussed from study methods, affecting factors and applications. Results showed that the fecundities were different in different species, and related to latitude. The development of ovary was exogenous factors, neural incretion and environment. controlled by a complex interaction of endogenous and Hormones and neurotransmitters control the maturation of the ovary. Temperature, salinity, nutrition, and photoperiod also affect the maturation of the ovary. Weighting and slicing were the traditional and main ways to study the fecundity and ovary, respectively. Volume and dissection are potential ways to do fecundity researches. Results also showed that studies of ovary development should be combined with basic biology of crab, especially physiology, life history and behavior.