Objective: To understand the impact of left behind experience on the mental health of secondary vocational school students, so as to provide theoretical basis for the psychological health education of secondary vocational school students. Methods: From September to December in 2019, a total of 3 401 students from Duyun, Guiding and Pingtang County were selected by multi stage cluster random sampling method. Self designed questionnaire and Symptom Check List-90(SCL-90) were used to investigate mental health status. A total of 1 415 left behind students and 1 415 non left behind students were matched by using propensity score matching (PSM). Wilcoxon test and Logistic regression analysis were conducted. Results: Before the matching of propensity score, there were statistically significant differences in the distribution of family structure, mother s educational level, family residence,family harmony and children s past health among the students with or without left behind experience ( χ 2=28.17, 52.40, 96.31, 29.75 , 19.10, P <0.05). After the matching, there were no statistically significant differences in the distribution of the above variables among the students with or without left behind experience ( χ 2=0.02-4.32, P >0.05). Before the matching of propensity scores, there were significant differences in the scores of 10 dimensions of SCL-90, including somatization (1.67,1.58), interpersonal sensitivity (2.00,1.89), anxiety (1.90,1.70), obsessive compulsive symptoms (2.20, 2.10), depression (2.00, 1.85), hostility (1.83, 1.67), terror (1.85, 1.71), paranoia (1.83, 1.67), psychotic (1.70, 1.60) and other (1.85, 1.71) dimensions among secondary vocational school students with or without left behind experience ( Z=-5.15 to -2.84, P <0.05). After propensity score matching, there were significant differences in scores remained only in three factors for interpersonal sensitivity [(2.00(1.56,2.67)，2.00(1.44,2.56)], paranoia [1.83(1.33,2.50)，1.83(1.33,2.33)] and psychoticism [1.70(1.30,2.30)，1.70(1.20,2.20)] in SCL- 90 among secondary vocational students with or without left behind experience ( Z=-2.45, -2.12, -2.23, P <0.05). Conclusion The impact of left behind experience on the mental health of vocational school students is mainly reflected in interpersonal sensitivity, paranoia, and psychoticism, which should be identified as key areas of psychological education for secondary vocational school students.