Objective: To investigate the status of knowledge about acquired immune deficiency syndrome(AIDS) among college freshmen in Jiangsu Province, and to analyze the influences of AIDS-related knowledge on their sexual attitudes and behaviors. Methods: A total of 8 633 freshmen from 20 colleges and universities in Jiangsu Province were enrolled by multi-stage stratified sampling. The questionnaire for young students about the eight items of AIDS basic knowledge were used to investigate the AIDS-related knowledge, sexual attitudes and behaviors. Multivariate Logistic regression model was used to analyze the influencing factors of the AIDS-related knowledge and to adjust the influences of AIDS-related knowledge on sexual attitudes and behaviors. Results: The overall qualified rate of AIDS-related knowledge among college freshmen in Jiangsu Province was 87.6% and the qualified rate of 8 items were between 59.8% and 98.3%. The types of schools, nationality, mother s education level and whether only child or not were identified as independent factors for qualified rate of AIDS-related knowledge(P<0.05). The awareness of AIDS-related knowledge had significant impacts on the sexual attitudes and behaviors of college freshmen. Students with insufficient knowledge were more likely to approve premarital sexual behaviors(OR=1.31, 95%CI=1.11-1.63), willing to use condoms consistently(OR=1.67, 95%CI=1.43-1.92) and to accept the HIV tests(OR=4.54, 95%CI=3.13-6.52). Students with unqualified knowledge were more likely to have sexual behavior(OR=1.89, 95%CI=1.42-2.49), while those with sexual experiences and insufficient AIDS knowledge were more likely to use condoms consistently(OR=2.13, 95%CI=1.22-3.78). Conclusion The education on AIDS-related knowledge for teenagers was helpful to construct correct sexual concepts and develop healthy sexual behaviors. However, the AIDS-related knowledge of college freshmen in Jiangsu Province is not sufficient and needed to improve.