This article tries to understand the Martial offense in the Northern Wei Dynasty, including cowardice in the war, hesitated to stay in the war, overdue the agreed date in the war, undermined the military strategy and action, poor military discipline, lost the army, fraud obtained military exploits, stealing military supplies, unauthorized to enslave soldiers, failed of war, and poor military performance etc. These martial offense might disturb the order of battle, violated military operations, hurt soldiers' lives and damage to the national interest. Therefore, in order to maintain military discipline, fighting force, the ruler must punish officials for military offenses. In addition, recognizing military offense in the Northern Wei Dynasty, we can also learn the development of the ancient military law.