Abstract: Objective To understand the changing and change trend of risk sexual behavior among men who have sex with men(MSM)in Kunming.Methods Behavior surveillances questionnaire was conducted by face-to-face interview among different resource MSM,including from park,bar,bathing room,or those who seldom go to public place.Results The mean of sexual partner increase from 112 in 2004 to 212 in 2006.The general rate of knowledge on HIV/A IDS among MSM increase from 75.3% in 2004 to 86.3% in 2006.During the last 6 months,the rate of condom use increase from 32.3% in 2004 to 73.8% in 2006 in every commercial anal sex,and the rate of condom use increase from 30.5% to 51.1% in no- commercial anal sex.50% of MSM have sex with women,but the condom use rate increase from 24.4% to 26.6%.Conclusion Year by year,the general rate of knowledge on HIV/A IDS and the use rate of condom in MSM increase,but it is difficult to understand which is the main influence factor of condom use.MSM is still the high risk people of HIV prevalence.