Abstract: The fight between the kings of imperial clan was lasting at the last phase of the Western Jin Dynasty, after the Min Emperor was captured by Liu Yao, Sima Bao and Sima Rui fought for the emperor seat, they all claimed themselves ‘the Jin King’.In order to become himself the unique heir of the Jin Dynasty,Sima Rui did everything possible to collapse the strength of defence against the Northern barbarian in ancient China, which was the basis of the Sima Bao's Jin regime kept going, even by borrowing a knife from Duan Pidi to kill Liu Kun who was the main force of defence against the Northern barbarian in ancient China.The result of the fight was that Sima Bao became extinct under the Northern barbarian in ancient China's hard press,Sima Rui became the emperor who founded the East Jin Dynasty in Jiankang replaced the West Jin Dynasty in Luoyang.