Abstract: This paper analyzes the methods of constructing student portraits that serve the precise ideological and political work in colleges and universities based on educational big data， puts forward the data resource content， hierarchical label system and model building methods of student portraits， explores the application of cluster analysis method， outlier analysis method and association analysis method in the precise ideological and political work， and proposes the portraits of college students' personality analysis， refined ideological and political education portraits， isolated behavior map portraits， college students' academic warning portraits， college students' comprehensive quality evaluation portraits， Internet addiction correction strategies portraits and the precise ideological and political work paths. The paper summarizes the key links and technical ethics of the precise ideological and political work model， and puts forward four suggestions for data resource construction， in-depth portrait development， work practice paths and ideological and political technological ethics.

Key words: ideological and political education; precise ideological and political work; student portraits; big data