Granuiosa cells (GCs) are the most important cells in the ovary that undergo serious changes morphologically and physiologically during the processes of follicular proliferation, differentiation, ovulation, lutenization and atresia. Oocyte (OC) directs GC proliferation and differentiation, while GCs influence OC maturation. Many ovarian factors are involved in the regulation of these processes via different molecular mechanisms and signal pathways. P38MAPK can selectively regulate steroidogenesis in GCs controlled by FSH; Transcript factors LRH-1 and DAX-1 play an important role in this process; FSH induces GC prolfferation and differentiation by stimulating PCNA and StAR expression and steroidogenesis. Activated ERK1/2 signal pathway may be involved in the FSH-regulated GC proliferation and differentiation. Therefore, GC is an ideal model for studying cell proliferation, differentiation and interaction,as well as signal transduction. This review briefly summarizes the latest data in the literature, including the results achieved in our laboratory.