Abstract: To explore the relationship between proactive personality, perceived teachers'support, positive emotion and learning engagement among junior middle school students, a total of 624 junior middle school students were surveyed using the Proactive Personality Scale, Perceived Teachers'Support Scale, Positive Emotion Scale and Learning Engagement Scale. The results show that:(1) Proactive personality was positively correlated with perceived teachers'support, positive emotion and learning engagement; Perceived teachers'support was positively correlated with positive emotion and learning engagement; Positive emotion was positively correlated with learning engagement. (2) Perceived teacher support and positive emotions play a significant mediating role in the influence of proactive personality on learning engagement of junior middle school students, which contained three mediating paths-the mediator of perceived teachers'support; the mediator of positive emotion; the chain mediating role of both perceived teachers'support and positive emotion. The results show that proactive personality not only directly predicted the learning engagement of junior middle school students, but also indirectly predicted learning engagement through perceived teachers'support and positive emotion. The results suggested that the effects and mechanisms of proactive personality on learning engagement, which is provide effective theoretical basis for improving the learning engagement level of junior middle school students.