Objective To explore the key influencing factors of HIV risk behavior among male who have sex with male (MSM). Methods 36 MSM subjects in a community were recruited for HIV risk behavior characteristics, social environment and the attitude of exposure of high risk sexual intercourse, using behavior scales and qualitative research methods. The collected data were orderly input and analyzed using Nvivo 8.0 software. Then, after three-level transcription, the data were further summarized and extracted based on the method of the grouding theory. Results The HIV Risk Assessment Questionnaire score of 36 subjects was 8.08±2.46, of whom, 72% scored at a medium level (5 to 10 scores) and 19% scored at a high level (more than 10 scores). The social support rating scale (SSRS) score was 32.38±5.99 in MSM population, lower than in undergraduates and floating population. The results of qualitative analysis showed that, after open coding, 11 key message and 4 categories contributed to HIV risk in MSM populaiton, including: a) low levels of fear for AIDS; b) male role and uncertain sexual orientation; c) low degree social support; and d) poor availability of condom in the setting of sexual intercourse. Conclusion The interventions against AIDS/HIV for MSM need to be further studied. Besides, we should strengthen the community intervention mode based on fear for AIDS, social support, and condom distribution methods