Abstract Background To date, a large proportion of people still suffer from diarrhea diseases. In addition to the burden of diarrhea, there are substantial social and economic costs caused by the high incidence of diarrheal diseases. Therefore, the purpose of this study was to explore the self-reported prevalence of diarrhea and associated risk factors of diarrhea among adults in Beijing, China. Methods A multistage, stratified study based on cross-sectional data was performed using randomized and systematic sampling, recruiting 12,936 adults over 18 years of age in Beijing. All adults were requested to complete a questionnaire, including information such as demographic characteristics, incidence of diarrhea, and behaviors related to the diarrhea. Results The self-reported prevalence of diarrhea was 17.5% during the last year prior to the survey. Six behavioral factors were significantly associated with diarrhea in our study including: (1) washing hands before meals and after defecation (Adjusted Odds Ratio (AOR) 0.707, 95% CI 0.597 ~ 0.837), (2) washing hands with soap and running water (AOR 0.872, 95% CI 0.786 ~ 0.967), (3) consuming raw seafood (AOR 1.285, 95% CI 1.138 ~ 1.450), (4) using the same chopping block and knife when processing raw and cooked food (AOR 1.375, 95% CI 1.225 ~ 1.542), ( 5) using the same chopsticks to handle raw and cooked food (AOR1.149, 95% CI 1.041 ~ 1.268), and (6) regularly participating in physical exercise (AOR 0.719, 95% CI 0.651 ~ 0.793). Conclusion Good health habits, good eating habits, and regular exercise can prevent the episodes of diarrhea, and thus decrease the potential for disease occurrence.