Major Histocompatibility Complex(MHC), further divided into Class I, II and III regions，is an organized cluster of tightlylinked genes widely distributed in the vertebrates. Owing to the high gene polymorphism, the ovine MHCⅡ has received increasing focus of study on genetics, evolution and breeding for disease resistance. The present study reviewed the recent advances of MHCⅡgene polymorphism and its disease association in different sheep breeds, and prescribed its research in the future.