There is a lack of quantitative studies on the acceptance of extramarital sex in China. Based on data from the Chinese General Social Survey 2013 (CGSS2013), this paper used a zero-inflated Poisson regression model to analyze the factors influencing the public's attitudes toward extramarital sex. When other variables were controlled, groups of younger ages, higher educational levels, and stronger tendencies toward "liberalization" and non-Islamic beliefs were more tolerant toward extramarital sex, whereas gender and Christian beliefs had no significant influence. In this regard, family and marriage counseling, and society's moral tolerance and social control of religion are discussed, and further research on cross-cultural verification is needed.