The aim of this essay is to research into Mengzi’s good at the application of I‐ching in order to state his views of the political philosophy. In the Book of Mengzi, there is not any one word about I‐ching but a useful application of I‐ching also, which studies the way in power and explains his thought what he wants to say. Mengzi , by way of his application of I‐ching, is going to try to make his political philosophy public in the countries. Thus, Mengzi’s famous idea is belong to developing Kongzi’s and to becoming the Chinese traditional theory such as Minben（民本）, Xujun（畜君）, Shuren（熟仁）. The philosophy of Mengzi’s is in the understanding practical basis of power life. Through this thinking with applying I‐ching, Mengzi makes great efforts to I‐ching’s(Yi‐Study 易学) development for Mengzi opens the way in the application of I‐ching.