Objective: Aim of this study was to determined the factors associated with physical activities among school children Methods: This cross-sectional study was carried out with school children (n = 603) who studied in a rural district in Sri Lanka. Self-administered questionnaire was implemented to collect information on behavior related to the PA among school children. Weight and height of children were measured according to the standard protocols and BMI was calculated. SPSS 20.0 version was used to analyze the data. Results: The sample composed 603 students age from 13~16 years old, 49.4% were males. Results indicated that mean BMI of the students was 18.145 Kgm-2 (SD = 3.28, CI = 95%). More than half of children were found to be underweight. Results indicated that 8.9% students did not have engaged with any kind of physical activities while 18.1% were physically active two days per week during past seven days. Further 20.9 % students used walking and cycling to go to the school one day per week. And also 35% walked and cycled two days per week. Majority of students (64.0%) did not participate to the physical activity period while 44.0% student had sedentary behavior at least one to two days per week. Only 2.0% of students did not active for more than eight hours per day during past seven days. It was observed that 27.0 % students were sedentary three to four hours per days during past seven days. Conclusion: Prevalence of PA among the rural school students found to be low and the sedentary behavior was prominent among the group. Proper health intervention and establishing policies should be encouraged.