Objective: To explore the relationships among social support, depression, anxiety and suicide ideation among middle school students in rural areas of south Sichuan Province so as to provide a scientific basis for promoting middle school students’ mental health and reducing suicide ideation. Methods: A sum of 2 217 students of grade 7 and 10 from 2 township middle schools in mountainous areas of Zizhong County, Sichuan Province, were investigated by means of typical sampling and cluster random sampling. Social Support Rating Scale (SSRS), Self-rating Scale for Depression (SDS), Self-rating Anxiety Scale (SAS) and Self-compiled adolescent health questionnaire were used to measure suicidal ideation, and structural equation model was used for statistical analysis. Results: The depression score of middle school students was (13.51±12.57), and the self-rating scale for Depression score of girls was (14.61±12.67), higher than that of boys (12.24±12.34). The SSRS score of Social Support Rating Scale of junior high school students was (35.49±5.88), which was higher than that of senior high school students (34.70±5.43), and the differences were of statistical significance(t=4.46, 2.67, P<0.05). The results of structural equation model showed that depression and anxiety directly affected suicidal ideation, and the standardized effects were respectively 0.11 (95%CI=0.06-0.16) and 0.09(95%CI=0.05-0.14). Depression and anxiety were the intermediate variables in the relationship between social support and suicidal ideation, and the mediating effects were respectively -0.46(95%CI=-0.51--0.41) and -0.21(95%CI=-0.27--0.16). Studying period could play a mediating role in the indirect effect made by social support on suicide ideation through anxiety. Conclusion Anxiety and depression have significant mediating effect on the relationship between social support and suicidal ideation among middle school students in rural areas of south Sichuan province. Anxiety and depression intervention are important measures to reduce suicide ideation among low social supporters.