Abstract: To solve the unity problem in rational utilization,Kant puts practical rationality in a prior position according to logic,while Mou Zongsan regards that morality is prior to knowledge according to traditional Chinese source.Comparing the two,we may find that moral priority is the precondition for Kant and Mou Zongsan to propose moral metaphysics respectively,and it will certainly lead to moral idealism to be tested by practice.

Key words: moral priority, Mou Zongsan, Kant, moral metaphysics