One hundred junior high school students were selected as subjects and asked to complete the SCL-90 scale, the Big Five Brief Personality Inventory, and the Adolescent Peer Self-Representation Questionnaire to explore the relationship between self-representation, personality traits, and mental health. The results revealed that: (1) Junior high school boys were better at self-presentation of their personality traits than girls; (2) Eighth grade students were better than seventh grade students in terms of hobbies, interests, and physical development; (3) Junior high school students' self-presentation behaviors helped cultivate extroversion, friendliness, and openness, and promoted parentchild relationships and learning ability; (4) Self-presentation promoted the development of positive personality traits; (5) There is no correlation between self-presentation and SCL-90. The above results suggest that the self-expression line of junior high school students is conducive to promoting the formation of a healthy personality, which in turn is conducive to promoting mental health. The content of the activities advocating the use of self-expression for excavation and junior high school students is that schools, families, and society need to establish a correct concept of education.