Objective: To analyze the epidemiological characteristics and associated factors of delayed voiding among middle school students, and to provide the basis for health education. Methods: A total of 1 260 middle school students were selected from Sanmen country in Taizhou by using multi-stage stratified sampling method. A cross-sectional survey was conducted to investigate the demographic characteristics, epidemiological characteristics and associated factors of delayed voiding by questionnaire. Results: The proportion of frequent delayed voiding among middle school students was 14.37%(181). The proportion among senior high school students was 15.51%(90), and among junior high school students was 13.67%(91)，no significant differences were found by grade(χ2=0.57, P=0.45). The multivariate Logistic regression analysis showed that residential school, homework per day >2 hours, games and reduce the frequency of drinking ≥7 times/week were risk factors for delayed voiding frequently in junior high school students(OR=3.71, 1.70, 3.02,6.52，P<0.05). Higher than 2 hours of daily homework, a supportive or indifferent attitude to delayed voiding, staying in bed after waking up, drinking <0.5 L/d or ≥2.0 L/d, and reduce the frequency of drinking ≥7 times/week were risk factors for delayed voiding behavior in high school students(OR=2.23, 1.81, 2.22, 3.48, 2.69, 3.00, P<0.05). Conclusion The prevalence of frequent delayed voiding was high among middle school students. Attitude, environment and the quality of drinking water were the primary factors of frequent delayed voiding.