Han Fei was a native of the state of Han before he went to Qin to present his writings to the future emperor. The emperor was pleased with his ideas and employed him as an ambassador. While Li Si was the politician, Han Fei was the theoretician of Legism at the court of the King of Qin during the late Warring States period. When he came back Han, he was arrested and charged having secret relations to his home state. He was forced to drink poison.

The Han Feizi is a work written by HanFei at the end of the Warring States Period in China, detailing his political philosophy. It belongs to the legalist school of thought, and it is valuable for its abundance of anecdotes about China of pre-Qin times. The Han Feizi include fifty-five treatises which are collected into twenty books and which are mainly concerned with what the ruler of a state should do in order to acquire and maintain political power. The treatises describe the strategies which a ruler may employ in order to maintain control over the legislative functions of government. The treatises also describe the actions which a ruler may take in order to prevent usurpation of power by other government officials, and discuss the tactics which a ruler may employ in order to maintain supreme authority.

Han Fei was a disciple of Xunzi, and the most important element of Confucianism in his thinking was the relationship between ruler and minister. If anyone behaved wrong, he had to correct his attitudes according to his right position in the social structure. In the legist state, everyone had to act to the welfare of the state. Only a strong state could exist in a world of warfare where each state fought against each other. The center of the state was the ruler who had to keep care that none of his ministers had ambitions to overthrow him. He was the state itself, pivot and kernel of a state structure that worked by itself once established. Taoist thinking can be seen in such a state where the ruler rules by doing nothing. Practically, the ruler had to initiate behaviour standards, controlling methods and controlling strength. He argues that human nature is basically selfish and deceitful, and that the best way to motivate subjects to be loyal to a ruler is to reward them for loyalty and to punish them for disloyalty. This ethically pessimistic viewpoint was influenced by the moral philosophy of his teacher Xunzi, who argued that human nature is basically evil and that moral goodness can only be acquired through conscious effort or training.