Online political communication is an important factor affecting the political identity of youth, and political psychology plays an important mediating role in the process. Clarifying the mechanism through which online political communication affects the political identity of youth is an important step to accurately interpret the relationship between them. Based on the survey data of 1647 young people, this paper analyzes the impact of different types of online political communication on the political identity of youth, and further explores the impact mechanism. It is found that positive information and online political interaction help to enhance the political identity of youth, negative information reduces the political identity of youth, online political expression and online public participation play the dual role in the political identity of youth, among which authoritarian values and political efficacy are the mediating variables between online political communication and the political identity of youth. Creating a good environment for information dissemination and participation in interactive spaces is helpful to promote the active constructive identity of young people, which is very important to enhance the political identity of youth.