Objective: To understand and analyze the mental health status of key Senior School Students at grade 3 in Haidian District of Beijing and Senior Three Students in General Schools, so as to provide basis for mental health education and psychological intervention. Methods: A total of 263 senior three students were randomly selected from a general school and two key school in Haidian District of Beijing. A questionnaire survey was conducted using the Mental Health Scale for Chinese Middle School Students (MSSMHS). Results: Of the 260 students surveyed, 54.2% had mental health problems, 36.5% had mild problems, 8.8% had moderate problems, and 0.5% had slightly and deeply serious problems. The first three factors about examined rates of factors of mental health were anxiety, learning and interpersonal relationship. The detection rates accounted for 23.5%, 23.1% and 18.8% respectively. There was no significant difference in the scores of each factor between key and ordinary middle school students (P>0.05). The scores of interpersonal, depression, anxiety and emotional factors of middle school girls were higher than those of boys, with statistical significance (P<0.05). Conclusion: There are some mental health problems among senior students at grade 3 in Haidian District of Beijing, and female students’ are serious. Schools, families and societies should pay attention to this problem and strengthen mental health education with a focused goal.