Abstract: Objective To determine risk factors of school-based clustering outbreak of tuberculosis (TB) and to provide evidence for tuberculosis prevention and control.Methods A case-control study was conducted in 9 schools with clustering of TB patients as case group and 37 schools which only single TB patient without TB clustering as control group in Shaoxing city from 2011 to 2015.Risk factors of TB clustering in school were analyzed between the two groups.Results The time interval between first case and initial report was (80.89 ± 76.82) days in case group and 27.81 ± 24.28 days in the control groups (t=3.58,P=0.01).The time interval between first case and initial report to the CDC was (81.11 ± 76.69) days in case groups and (28.29 ± 24.32) days in the control (t=3.64,P =0.01).Time interval between first case and investigation was (82.00± 76.88) days in case group and (30.37±24.88) days in control group (t =3.49,P=0.01).There was no significant differences in morning check-up,absence registration,reasons tracing,suspended students returning to school,infectious disease emergency response plan,and infectious disease reporting system between the two group.No significant differences in terms of physical examination of students,PPD screening,the school doctor,full-time school doctor,infectious diseases school training for doctor,health education of infectious disease prevention were found between two groups.Conclusion Delayed diagnosis and report correlates with TB clustering in school.Early detection and report on first TB case is key for the prevention of school-based TB clustering.