To investigate the prevalence of overactive bladder (OAB) and assess its risk factors in 5- to 14-year-old Chinese children. A cross-sectional study of OAB prevalence was performed by distributing 11 800 anonymous self-administered questionnaires to parents in five provinces of mainland China from July to October 2018. The questionnaires included questions on sociodemographics, history of urinary tract infection (UTI), lower urinary tract symptoms (LUTS), family history of LUTS, bowel symptoms, and details about the elimination communication (EC) start time. OAB was defined as urgency and increased the daytime frequency with or without urinary incontinence. A total of 10 133 questionnaires qualified for statistical analysis. The overall prevalence of OAB was 9.01% and decreased with age, from 12.40% at 5 years to 4.55% at 14 years (χ2 trend = 88.899; P < .001). The proportion of dry OAB increased with age, whereas the proportion of wet OAB decreased. A late-onset of EC was associated with a high OAB prevalence (χ2 trend = 39.802; P < .001). Children with obesity, a history of UTI, nocturnal enuresis (NE), a family history of LUTS, constipation, and fecal incontinence had a higher prevalence of OAB than did normal children (P < .05). Obesity, a history of UTI, NE, a family history of LUTS, and bowel symptoms are risk factors associated with OAB. Starting EC before 12 months of age might help reduce the prevalence of OAB in children. © 2019 Wiley Periodicals, Inc.