Objective: To analyze the role of school based symptom monitoring system in public health emergencies in Hangzhou, to provide the basis for prevention and control strategies for public health emergencies in schools. Methods: Data regarding school public health emergencies in Hangzhou in 2019 were collected from the Public Health Emergencies Report Management Information System, and data regarding public health early warning in schools were collected from the Hangzhou School Symptom Monitoring System. The usage of school symptom monitoring system was analyzed by SAS 9.0 software, and the positive warning events and public health emergencies were compared and analyzed, the rate and composition ratio were compared with the χ 2 test, the number of cases was compared with the non parameter rank and the Mann Whitney test, and the trend test was conducted using Cochran Armitage test. Results: In 2019, the average use rate of the city s school symptom monitoring system was 54.65%, the average response rate of automatic early warning was 70.68%, and the use rate (χ 2=860.79, p<0.01) and automatic early warning response rate (χ 2=1 615.91，P<0.01) of school systems varied greatly by region. In 2019, 161 positive early warning incidents were detected through the school symptom monitoring system, 197 public health emergencies were reported through the emergency network, and fewer public health emergencies were reported in areas where more positive warning events were detected(Z=10.65，P<0.01). The proportion of disease category in positive warning events was different from that in public health emergencies in(χ 2=28.33, P<0.01). The number of cases of positive early warning events of the same disease was much lower than the number of cases of public health emergencies without warning, and the time of positive warning signals was on average 4 days ahead of the time of receiving the report of public health emergencies. Conclusion Smartphone based school symptom monitoring system in Hangzhou plays a sentinel role in public health emergencies prevention and control in schools.