As one of the oldest character all over the world, Kanji have been widely used in China, Japan, North and South Korea, Vietnam, etc. After the world war II, Chinese and Japanese both carry out a reform of Kanji and enacted new language policy. There are many similarities and differences between Chinese and Japanese Kanji reform. This study aims to compare Chinese and Japanese Kanji polity and reform regarding content and order of the reform, the number of the Kanji common usage list, the method of simplification, the role of Kanji common usage list. From the comparison, it becomes clear that the purpose of Japanese Kanji reform is number restriction. And on the other hand, the purpose of Chinese Kanji reform is simplification. And this paper clears up the reason why Chinese and Japanese purpose is different from the aspects of social and cultural background. Finally, this paper discusses the change of Chinese and Japanese Kanji policy by comparing with the present policy.