Abstract: Shang Yang was derogated by later generations of Confucian intellectuals because of harsh punishment. However, when we restore the objective conditions of Shang Yang reform period, we found that political reform had become inevitable to change the fate of the weak Qin State and the means of reform was to Strengthen the sovereign authority and run all kinds of national affairs by law. It was justified and necessary significance that Shang Yang formulated harsh punishment in implementing Agricultural War. Because of opposition to the orthodox position of Confucianism, the reforms of Shang Yang was affirmed harshly and ungenerously.