Objective: To analyze the characteristics of the daily exercise load and the One Hour of Moderate to Vigorous Physical Activity (MVPA) per day among primary school students, so as to provide a reference for improving the quality of the physical activity of primary school students in school. Methods: A total of 223 students from an elementary school in Beijing from May to June of 2023, were selected by stratified random cluster sampling method. The Polar Verity Sense heart rate arm band was used to monitor and evaluate the daily exercise load heart rate according to different grades, gender and physical quality. Results: The average heart rate of primary school students in outdoor class, zero point sports, recess and indoor class was (130.01±13.11, 119.89± 16.02,109.96±8.11,96.81±7.89) times/min, respectively, and only 4.04% students met the standard of 1 hour MVPA daily. From the perspective of different grades, the MVPA time ratio of lower grade students in outdoor class, zero point sports and big break was 28.41%, 42.47% and 8.24%, that of middle grade students was 18.33%, 6.41% and 5.90%, and that of senior students was 45.91%, 3.88% and 11.43%. The number of students who achieved 1 hour daily MVPA was 5.41%, 0 and 6.67%. Time ratio of MVPA in outdoor classes, zero hour sports and big breaks accounted for 30.09%, 16.34% and 9.23% for boys, 31.70%, 16.24 % and 6.13% for girls, and the interval distribution of boys and girls who achieved MVPA for one hour per day was 5.88% and 2.86%.Time ratio of MVPA for students with excellent physical fitness were 33.19%, 21.76% and 8.25% in outdoor class, zero point sports and big break, while those with good physical fitness were 29.76%, 12.93% and 8.19%.A total of 21.78%, 5.99% and 4.80% of the students passed the physical fitness test, and the number of students with excellent, good and passed the physical fitness test who achieved the daily 1 hour MVPA was 5.88%, 3.77% and 0. Conclusion In the present study, elementary and middle school students time for in school physical activity was adequate, but there are problems of low loading intensity and insufficient time for MVPA. It is necessary to arrange targeted physical activity programs for students of different grades, genders and physical fitness levels to increase the daily exercise load of students in school.