Objective: To analyze the relationship between cumulative ecological risks and physical activity behaviors of junior high school students, so as to provide theoretical support for promoting the physical and mental health development of junior high school students. Methods: From March to April 2023, a multistage random cluster sampling method was used to conduct an online survey of 3 502 middle school students in Henan Province. Physical activity levels and cumulative ecological risk were measured using the Physical Activity Rating Scale-3 and the Cumulative Ecological Risk Scale. Chisquare test and multiple Logistic regression were employed to examine the distribution and influencing factors of physical exercise behaviors among different student groups. Results: Slight physical exercise had the highest proportion of physical activity in tensity among junior high school students (48.5%), with 80.4% engaging in low levels of physical activity. Only 16.8% of students exercised ≥1 time daily, and the most common frequency was 1-2 times per week (44.1%). Gender, residential area, parental education, and peer support were all significantly associated with physical activity levels among junior high school students (χ2=122.53, 6.49, 7.49, 10.17, P<0.05). Logistic regression analysis showed that higher cumulative ecological risk scores were associated with a greater likelihood of engaging in low levels of physical activity compared to high levels (OR=1.12, 95%CI=1.02-1.23, P<0.05), but no significant association was found for moderate physical activity (OR=1.08, 95%CI=0.97-1.21, P>0.05). Conclusions Junior high school students in Henan Province generally engage in insufficient physical exercise. Cumulative ecological risk negatively predicts their physical activity behaviors.