Objective: To determine the latent class of dietary patterns and their association with depressive symptoms among first grade students from multi ethnic middle schools in Yunnan Province, so as to provide a reference basis for promoting mental health among border middle school students. Methods: A cluster random sampling involving 8 500 first grade middle school students from 11 counties in Yunnan Province was conducted by a questionnaire survey between October to December 2022. The Children s Depression Inventory (CDI) was used to assess the depressive symptoms and the Food Frequency Questionnaire was used to collect eating behavior data. The latent profile analysis model was used to fit the latent class of dietary patterns among students. The association between the dietary pattern latent class and depressive symptoms was analyzed by Logistic regression. Results: The depressive symptom detection rate among firstgrade middle school students was 28.3%. Prevalence of depressive symptom in girls (30.9%) was higher than boys (25.5%) with a statistically significant difference ( χ 2=29.83, P <0.01). The dietary patterns among first grade middle school students were classified into four latent classes, as follows:class 1 (low consumption of all dietary components), class 2 (high consumption of fruit, milk and dairy products), class 3 (high consumption of vegetables and meat, and low consumption of processed foods) and class 4 (low consumption of milk, dairy products and eggs, and high consumption of processed foods). After adjusting for confounding variables, the class 3 dietary pattern was negatively correlated with depressive symptoms ( OR=0.62, 95%CI =0.52-0.74) and the class 4 dietary pattern was positively correlated with depressive symptoms ( OR= 1.28 , 95%CI =1.05-1.57) ( P <0.05), compared with the class 1 dietary pattern. Conclusions Multi ethnic first grade middle school students in Yunnan Province follow various dietary patterns. Unhealthy dietary patterns increase the risk of depressive symptoms. The dietary patterns of multi ethnic middle school students in Yunnan Province should be adjusted to promote the establishment of healthy dietary patterns and reduce the risk of depression symptoms in middle school students.