Objective: This study aimed to explore the relationship between childhood sexual abuse (CSA) and sexual orientation among college students, and to explore possible sex difference. Methods: By using multi-stage stratified cluster sampling method, 4 034 students were selected from 4 college schools. Self-made questionnaire was used to collect the demographic information, CSA experiences and sexual orientation. Logistic regression models were conducted to examine sex differences in the relationship between different types and timing of CSA and sexual orientation. Results: The reporting rates of heterosexual, homosexual, bisexual and asexual orientation of college students were 93.2%, 0.7%, 3.7% and 2.4%, respectively. For males, contact CSA (OR=14.70, 95%CI=5.73-37.72), both contact and noncontact CSA (OR=4.33,95%CI=1.91-9.84) in elementary school or earlier were associated with sexual orientaion. non-contact CSA (OR=4.20, 95%CI=2.21-7.98), both contact and noncontact CSA (OR=3.57, 95%CI=1.65-7.70) in middle school were related to sexual orientation. However, for females, non-contact CSA (OR=1.78, 95%CI=1.02-3.13) and both contact and non-contact CSA (OR=3.13, 95%CI=1.35-7.23) in elementary school or earlier were associated with sexual orientation. Conclusion CSA experiences are associated with sexual orientation in sex-specific manner, with significant stronger association among males.