Abstract: Objective To study the mental health status of grade two students from the key senior schools with different demographics in Xi'an area.Methods A stratified cluster sampling was used to select the total of 604 grade two students from the two key senior schools in urban and rural areas of Xi'an as subjects. A questionnaire survey was applied in which the subjects were asked to fill the Middle School Students Mental Heath Scale (MMSMHS). The multiple factors that affect the mental health were statistically analyzed.Results The subjects with light and above psychological problems accounted for 27.8% of the total number of investigation in this area. Anxiety, emotional liability and study stress were the top three psychological problems. The total factor score, as well as the three individual factors, compulsion, study stress and emotional liability, were significantly higher in girl students (P< 0.05). For comparison between areas, rural students had higher scores than urban students in total factors, and the following individual factors, anxiety, study stress and imbalance. The differences were statistically significant between the different areas (P<0.05). Enjoying athletics, single child, getting along with parents and their fellows were the favorable factors for mental health.Conclusion There are some mental health problems in senior school students in Xi' an area. The factors affecting students' mental health included family circumstance, personality traits and study pressure. Thus, it is necessary to provide mental health guidance to senior school students.