Objective: To investigate the status of comorbidity of six common diseases among primary and middle school students in Shaoxing City, Zhejiang Province, so as to provide evidence for formulating strategies for comorbidity management, prevention, and control among primary and middle school students. Methods: From September to November 2023, students from 12 primary schools, 12 junior high schools, and 12 senior high schools in Shaoxing City were selected as study participants using stratified cluster random sampling method. Six common diseases, including myopia, malnutrition, overweight and obesity, dental caries, abnormal blood pressure, and abnormal spinal curvature, were assessed by vision measurement, physical examination, dental examination, blood pressure measurement, and spinal examination, respectively. Comorbidity was defined as the coexistence of ≥2 diseases. The detection rate and distribution of comorbidity patterns among the six common diseases were analyzed. Results: A total of 11 887 students were surveyed, including 6 187 boys (52.05%) and 5 700 girls (47.95%). The mean age of the participants was (12.37±3.20) years. Myopia, dental caries, overweight and obesity, abnormal blood pressure, malnutrition, and abnormal spinal curvature were detected in 7 224, 3 721, 3 199, 1 880, 952, and 272 students, with detection rates of 60.77%, 31.30%, 26.91%, 15.82%, 8.01%, and 2.29%, respectively. Comorbidity was detected in 5 340 students, with a detection rate of 44.92%. Comorbidity involving two diseases was detected in 3 853 students, with a detection rate of 32.41%; comorbidity involving three diseases was detected in 1 335 students, with a detection rate of 11.23%; and comorbidity involving ≥4 diseases was detected in 152 students, with a detection rate of 1.28%. The comorbidity patterns with relatively high detection rates were myopia combined with dental caries, myopia combined with overweight and obesity, and myopia combined with abnormal blood pressure, involving 1 111, 1 008, and 495 students, with detection rates of 9.35%, 8.48%, and 4.16%, respectively. The detection rates of comorbidity involving myopia and dental caries were relatively high among primary school students and junior high school students, at 7.31% and 12.05%, respectively. Among senior high school students, comorbidity involving myopia and overweight and obesity had a relatively high detection rate of 11.16%. Conclusions The detection rate of comorbidity of six common diseases among primary and middle school students in Shaoxing City was 44.92%, mainly involving myopia combined with dental caries, overweight and obesity, or abnormal blood pressure. The distribution of comorbidity patterns differed across school stages, with myopia combined with dental caries being more common among primary school students and junior high school students, and myopia combined with overweight and obesity being more common among senior high school students.