Objective: To evaluate the effectiveness of AIDS intervention programs on men aged 50 or over and having had non-marital sexual behavior. Methods: A community-based intervention/experimental and based on individual level study was adopted. Stratified sampling method was used. 12 townships/streets in Fuyang district of Hangzhou were identified as intervention or control group (six research sites each). All of the subjects in the township (street) were included. The inclusion criteria of study objects would include men aged 50 or older who reported having unmarried sex in the last year. Estimated sample size was 290, with each 145 in the intervention group and the control group. All the intervention group participants were provided with a total of 4 intervention-related items (knowledge and education on AIDS prevention, information radiation and behavioral change, broadcast expert lectures), every 3 months, for 12 month, the main evaluation indicators would include: incidence of non-marital sex and commercial sex in the last year, condom use when having non-marital sex in the last episode. Results: A total of 312 subjects were recruited. 300 of them completed the baseline study while 284 of them completed the follow-up survey. Among the subjects who had undergone the baseline study, the average age was (65.58±7.89), 71.33% were married or cohabiting with someone, 52.00% having had primary school education. After the implementation of intervention programs, the incidence of non-marital sex dropped to 59.42% (82/138) and the incidence of commercial sex dropped from 79.73% (118/148) to 55.07% (76/138). Condom use rate in the last non-marital sexual contact increased from 19.59% (29/148) to 51.22% (42/82). In the control group, the incidence of non-marital sex in the year before dropped to 74.66% (109/146) and the incidence of commercial sex dropped from 91.45% (139/152) to 72.60% (106/146). Rates of condom use during the last non-marital sexual contact dropped from 32.89% (50/152) to 31.19% (34/109). Statistically, there were significant differences appeared between the two groups on the incidence of non-marital sex in the past year (χ²=7.48, P=0.008), the incidence of commercial sex in the last year (χ²=9.47, P=0.003) and the rate of condom use in the last sex experience (χ²=7.83, P=0.007). Conclusions Results from this intervention study showed that: in the intervention group, both the incidence rates of non-marital or commercial sex had reduced, together with the increase of condom use in non-marital sex in the last sexual experience. Intervention strategies that involving knowledge and education on AIDS prevention, information radiation and behavioral change, broadcasting lectures by experts etc. were all proved effective.