In the history of our country, there are also records about leverage. Mohist school in the Warring States period once summarized this law, and there are two special records about the principle of leverage in Mohist book. These two articles elaborated the balance of leverage very comprehensively. There are equal arms and unequal arms inside; Some change the weight of both ends to make it biased, and some change the length of the two arms to make it biased. Such a record is also very valuable in the history of world physics.