Objective: To explore senior high school students' knowledge, behavior and attitude toward sex and reproductive health issues. Methods: Questionnaire surveys were carried out in 6 high senior schools in Harbin, the questionnaire was provided by YRH (youth reproductive health) Project Team. Results: The after-school life of our sample included reading, watching movies and television, Internet exploring and playing with partners; 30%-40% of the people had never explore sex topic with their parents. Most of the students had appropriate understanding of adolescent knowledge, but they had less knowledge about reproductive health and contraception; About 30% of students had fallen in lover, only 4.3% of students had intercourse with their partners, and they were lack of awareness and ability to protect themselves from unsafe sex. 31.6% of students think that the main sources of knowledge of adolescent health education in schools. Conclusion: Students in senior high school have showed a more positive and stable attitudes toward life. They have some knowledge about YRH but not systematic.