Objective: To explore the PE sport load and its influencing factors of primary school students and to provide the basis for scientific and reasonable arrangement of PE sport load and increase its exercise effect. Methods: A total of 208 students from grade 5 and grade 6 of Small Wild Goose Pagoda Primary School in Xi an were selected. Stopwatch and PolarOH1 photosensitive heart rate sensor were used to record the time of each PE lesson, the students practice time and the continuous heart rate of the students during PE lesson. The exercise intensity and sport load of PE lesson were calculated by heart rate interval and training impulse (TRIMP) to evaluate the scientific nature and effectiveness of physical education. Results: The average continuous heart rate was (132.5±15.2)time per min. The primary school students PE classes were mainly of low moderate intensity, and moderate to vigorous physical activity (MVPA) accounted for 36.7% of the total class time.The average TRIMP of PE was (76.62±26.69). The average exercise density was 53.6%, and the average time of preparation, basic and end parts was 13.32, 25.57 and 0.50 min, respectively. Conclusion The PE intensity and TRIMP of primary school students are too small, the cumulative time of MVPA is insufficient, the PE exercise density is appropriate, the preparation part is too long, and the end part is too short. Therefore, the PE exercise load should be strengthened to improve the sports quality of PE students.