From A.D.42 to A.D.562，there was a Gaya federation consisting of some small countries existed at the basin of Nakdong river. Just as the Silla，Paekche and Koguryo，Gaya held a broad territory on Korean Peninsula. The history of Gaya confederacy maybe divided into two parts roughly：The earlier period of Gaya federation （from A.D.1st century to middle of 5th century） took Pusan and Gimhae area as the center；the later period of Gaya Kingdom （from the late 5th century） took Daegaya as the head which is located at Goryeong county of North Gyeongsang Province. The Gaya had already achieved the high level culture which is generally reflected on its ancient grave culture. At present，the research system frame，i.e. the Three Kingdoms time didn’t conform to its historical facts and we should strengthen the research on the history of Gaya.