This paper aims to investigate high school students' attitudes on sexuality and their information sources via an online questionnaire. The respondents were composed of 89 girls, 66 boys, and 5 students who identify as non‐binary, from 14 to 19 years old. Respondents were asked questions measuring their attitudes in four categories: sex orientation, sexual intercourse, romantic relationship, and sex education. In each category, gender differences, educational background and sources of their information are also analyzed. A gender difference was found: high school boys have more casual attitudes towards sexual intercourse though they also tend to acquire less knowledge about sexuality than girls, for example on the methods of contraception. Moreover, students in international environments were found to have higher acceptance of controversial issues regarding sexuality while domestic Chinese high schoolers responded more conservatively on these topics. High school students get their information largely from sources of media including movies, social media, and websites. Future research aims to introduce sex education to increasing numbers of schools as well as to impart professional knowledge about sexuality to students who are in earlier stages of education.