INTRODUCTIONTobacco smoking and alcohol drinking are strongly paired behaviours, affecting millions of people worldwide. Studies in western countries demonstrate that alcohol use among smokers makes it harder to quit smoking, and addressing alcohol use is particularly important for smoking cessation, but the evidence is limited in China. We conducted a cross-sectional study to understand the prevalence of smoking, drinking, as well as tobacco and alcohol co-use, and to explore how smoking cessation mutually facilitates drinking cessation among tobacco and alcohol co-users.METHODSDuring 2016 and 2017, we sampled 36698 participants aged >18 years in Songjiang district, Shanghai. A questionnaire was designed to collect data, and participants were classified into non-smokers and smokers (current and former smokers), as well as non-alcohol drinkers and alcohol drinkers (current and former alcohol drinkers). SAS software was applied to analyse the differences by weighted logistic regressions.RESULTSThe prevalence of tobacco smoking, alcohol drinking, and tobacco and alcohol co-use was 23.53%, 13.52% and 9.85%, respectively. Smoking cessation prevalence was 15.93%, which was higher than drinking cessation prevalence (8.22%). Tobacco and alcohol co-users had a higher prevalence of smoking cessation (16.95%) than participants who were only smokers (15.20%) and had higher prevalence of alcohol drinking cessation (8.71%) than residents who were only drinkers (6.91%). Tobacco and alcohol co-users who stopped alcohol drinking were much more likely to stop smoking than those who still drank alcohol (OR=8.83; 95% CI: 6.91–11.28) or those who only smoked (OR=7.51; 95% CI: 5.93–9.52).CONCLUSIONSDrinking cessation prevalence was lower than that of smoking cessation, and drinking cessation could mutually facilitate smoking cessation among tobacco and alcohol co-users. Tobacco smoking cessation programs could incorporate alcohol drinking cessation measures to achieve higher public health benefits.