Career exploration has always been the key to career development, but exploring the formation mechanism of career exploration behaviour from teachers' perspective is still inadequate. A three-stage time-lagged research design is used to obtain a valid sample of 1246 college students from mainland China. Based on self-determination theory, this paper analyzes the causal mechanisms of career exploration from the dual motivation of controlled motivation of teachers' support and autonomous motivation of future work self-salience of college students to explore the mechanisms and function boundaries of career exploration of college students. The results showed that: (1) Students' perceived teacher support positively influences career exploration; (2) Future work self-salience positively moderates the mediating effect of learning engagement on the relationship between perceived teacher support and career exploration. This research contributes to how to enhance the positive effects of career exploration are proposed.