Abstract: Ideological security is the lifeline of safeguarding core national interests and basic security. Ideological and political education in colleges and universities is an important carrier for effective dissemination of core socialist values and an important way to carry out and implement the fundamental task of morality education;it's also an important way to strengthen education for college students' ideals and beliefs. In the media era,the main structure of ideological education has undergone a qualitative change,and the alienation of media applications exacerbated the complexity of educational ecology. The lost of individual educational object in mediumlization environment has posed a great challenge to the ideological education in colleges and universities. in the new situation,in order to effectively maintain the security of national ideology,educators should play down the identity authority,strengthen professional ethics,and apply new media to their teaching. Colleges and universities should strengthen the construction of information media environment and optimize the social ecology of ideological education. Thus, the security of national ideology can get safeguarded with effects by strengthening the education of college students' media ethics and identity with mainstream ideology education.

Key words: mediumlization, colleges and universities, the security of national ideology, ideological education, core socialist values