Objective: To understand junior high school students’ sexual knowledge, sexual attitudes, sexual behaviors,as well as acess to sexual knowledge and related influencing factors, so as to provide reference for the practice of sexuality education. Methods: Using stratified cluster sampling method, 7 341 junior high school students were selected from Anhui, Fujian, Gansu, Guangxi, Henan, Xinjiang, Yunnan, Zhejiang and Beijing, and self-compiled questionnaires were used. Results: Junior high school students scored (61.71±18.79) in sexual knowledge, with pass rate and excellent rate being 59.02% and 18.53%. The attitudes towards LGBT was (65.44±20.01), the attitudes towards sexual and healthy behaviors was (67.04±49.23), and the attitudes towards sexual relations and behaviors was (70.75±10.46). Students had intimacy needs and sexual behaviors (18.70%), and some had such behaviors as kissing (13.80%), touching sensitive parts (6.70%) and sexual intercourse (2.20%). The results of multivariate Logistic regression analysis showed that students’ sexual knowledge was related to region, grade and school-based sexuality education (OR=2.11,P<0.05). Conclusion Junior high school students have sexual needs and behaviors, but their sexual knowledge is not sufficient; there are differences in sexual knowledge and attitudes of junior high school students across region,grade and gender; schools should promote school-based sexuality education for junior high school students’ sexual health.