Objective To investigate the prevalence of thyroid nodules among residents of Ningbo City and to explore the risk factors for thyroid nodules.Methods Totally 3 596 residents aged 6-70 were selected by multistage stratified cluster random sampling in Ningbo City,2011.Thyroid ultrasound examination was performed in all participants,while salt iodine and urinary iodine were measured.Possible risk factors for thyroid nodules were analyzed by single factor and multi-factor logistic regression.Results The prevalence rate of thyroid nodules in residents of Ningbo City was 22.66％ (815/3 596),with standardized prevalence rate of 17.69％.Female [(odds ratio (OR) =2.06,95％ confidence interval (CI) =1.74-2.43],groups of aged 18-(OR =3.42,95％ CI =1.22-9.61),aged 40-(OR =13.06,95％ CI =4.80-35.51),aged 65-(OR =16.67,95％ CI =5.97-46.54) and occasional consumption of seafood habits (less than twice per week,OR =1.23,95％ CI =1.02-1.49) were significant associated with thyroid nodules.Conclusions There is no link Letween iodine nutrition and thyroid nodules.It is demonstrated that female and aged ≥ 18 groups have higher risk of thyroid nodules; frequent consumption of seafood seems to be a protective factor.