In this paper, I aim to study on the Japanese language educational policy of the Japanese colonies of Taiwan, Korea, and Manchukuo before the war. I will start from the angles of "assimilation" and "Kominka movement" and discuss in terms of the changes of history and thoughts in the Japanese colonies: (1) the formation of thinking assimilation policy, (2) the colony Korea and its modern educational policies, (3) Manchukuo's citizen guidelines and Kominka education, (4) the interpretation of the construction of oversea temples and national theological thinking penetration. From these related issues, I plan to conduct a practical study on the content of the policies.