Abstract: Objective To understand the epidemiological characteristics of influenza outbreaks in Tianjin during 2013-2015 and explore the influence of the timeliness of outbreak reporting on the intensity of the outbreak. Methods The data of influenza outbreaks in Tianjin during 2013-2015 were collected for the correlation analysis. Results A total of 31 influenza outbreaks were reported in Tianjin during this period. The average attack rate was 3.54%. All the outbreaks occurred in schools, in which 77.41% occurred in primary schools. The pathogens were mainly influenza A(H3N2),influenza A (H1N1) and influenza B viruses. Correlation analysis showed that both the first reported case number and the interval between the first case onset and the reporting were positively correlated with the attack rate and duration of the outbreak . Conclusion Influenza outbreaks mainly occurred in schools in Tianjin. It is essential to improve the timeliness of the outbreak reporting and take early control measures to reduce influenza outbreak in schools.