Abstract: ObjectiveTo examine the incidence and associated factors of floating sexual behavior among men who have sex with men (MSM) in Mianyang city of Sichuan province.MethodsA self-administered anonymous questionnaire survey and serological testing under the informed consent were conducted among MSM recruited with snowball sampling at public places in Mianyang city between April and October 2014.ResultsAmong the 1 051 MSM with valid response,16.7% (175) reported floating sexual behavior and there was a significant difference in the ratio of reporting floating sexual behavior among the MSM living in different regions (χ²=274.330，P=0.000).Of the MSM reporting floating sexual behavior,29.9% (52),60.0% (105),8.6% (15),and 1.7% (3) had the sexual behaviors in nearby counties,urban area of Mianyang municipality,Chengdu city,and other cities or towns.The results of multivariate analysis showed that age,education,duration of living in local area,number of local gay acquainted,whether receiving preventive services,places for searching sexual partners,and the times of having anal sex during the latest week were independent influencing factors of floating sexual behavior (all P<0.05).ConclusionFloating sexual behavior among MSM is of demographic,regional and site specific characteristics and frequent floating sexual behavior among MSM increases the risk of transmission of human immunodeficiency virus and should be intervened with great effort.