FecB gene is a major gene responsible for high prolificacy firstly identified in Booroola Merino sheep. Subsequently, many other aspects of the FecB including endocrinology, fetal and postnatal growth were studied. A forced PCR-RFLP method was performed to screen some Chinese breeds or strains of sheep to determine if FecB gene is responsible for their high prolificacies. The FecB gene was present in some Chinese prolific breeds of sheep, such as Huyang, Small Tail Han (STH), Cele, Duolang sheep and Chinese Merino prolific strains, but absent in the low prolific sheep breeds such as Mongolia, Chinese Merino, Tan, Xinjiang, Hulunbeier, Inner Mongolia Fine Wool and Northeastern Half-fuzz Sheep. It has been confirmed that FecB gene was associated with high prolificacy in some Chinese breeds or strains of sheep. Moreover, introducing FecB gene to some low prolific breeds of sheep by crossbreeding system can improve the reproductive traits.