Objective To identify the levels of exposure to second-hand smoking (SHS)among Chinese adults living in the urban areas and their knowledge on the risks of SHS,to support for the Smoke-free policy.Methods Data from the Global Adult Tobacco Survey (GATS) and the International Tobacco Control Policy Evaluation China Survey (ITC China Survey) was analyzed and SAS was used to calculate the rates and 95％ CI.Results In the two surveys,less than 40％ of the respondents reported that their workplaces had completely stopped smoking.Participants who reported that they had seen people smoking at various public places with different rates,also they could reflect the levels to SHS exposure.Restaurants were the venue with the heaviest overall exposure (83.4％-95.6％),followed by the workplace (53.3％-84.0％).Exposure was low in health facilities,schools and public transport venues.In the GATS survey,60.6％ smokers and 68.5％ non-smokers believed that SHS could cause lung cancer,but only one-third of the participants believed that SHS could cause heart diseases in adults.Participants in the ITC China survey reported a comparatively higher level of awareness on the harm of SHS,but only 58.2％ smokers believed that SHS could cause heart diseases in adults.Overall,data from the ITC China survey showed that participants' support for a comprehensive smoke-free policy in schools,health-related facilities,government buildings and in taxi were high (over 70％).However,the proportion of participants supporting comprehensive smoking-free policy at workplaces (50.9％-60.9％) was relatively low.Conclusion The proportion of indoor workplaces with complete smoking ban was low in urban areas but levels to SHS exposure were high.People's awareness of harms related to SHS and their attitude on setting up a comprehensive smoke-free workplace need to be improved.