The Imjin War is the only cross-border military operation of the Ming Dynasty since the period of Yongle(永乐). Initially, the Ming Dynasty knew almost nothing about the dynamics of war between Korea and Japan, and hastily sent troops at the request of the King of Korea, therefore the Ming army were caught in a prolonged confrontation and stalemate with the Japanese army, which lasted for seven years. When the war broke out in the north of Korea, the soldiers of Liaodong, Jizhen(蓟镇) and Xuanfu(宣府) were still able to deal with it. However, when the war advanced to the southern region of Korea, due to the stretching of the front line, the increase of Japanese forces, and the continuation of the war, the Ming Dynasty had to mobilize the military forces of various regions and multi - ethnic groups within the country, and spent more than half of the total strategic reserve fund, and finally achieved the victory of the war together with the Korean army in the event of a sudden change in Japan. The various problems exposed by the Ming army and Ming Dynasty during the war had a significant and far-reaching impact on the political situation of the late Ming Dynasty, especially the situation in Liaodong.