Background Mobile phone dependence is a common problem in the population of high school students. We aimed to evaluate the core self-evaluation, mental health and mobile phone dependence in Chinese high school students, to provide reliable evidence to the support of high school students. Methods We conducted a survey of high school students in Xiamen, China. The self-assessment questionnaire on mobile phone use dependence among teenagers (SQAPMPU), Mental Health Scale for Middle School Students (MSSMHS) and Core self-evaluation scale were used to evaluate the mobile phone dependence, mental health and core self-evaluation. t-tests, Pearson correlation and multiple linear stepwise regression analyses were conducted to analyze the potential relationships. Results A total of 1692 students were enrolled. The total score of mobile phone dependence of students in grades 10–12 was higher than that of students in grades 7–9. A total of 329 students in grades 7–9 and 371 students in grades 10–12 had abnormal mental status. The detection rate of psychological abnormalities among students in grades 10–12 was higher than that of students in grades 10–12. Core self-evaluation had significantly negative correlation with various factors of mental health (P < 0.01). The worse the mental health, the higher the degree of mobile phone dependence, core self-evaluation played a mediating role between mental health and mobile phone dependence (8.03%). Conclusions Core self-evaluation is an important factor affecting the mental health of high school students and mobile phone dependence. Educators should strengthen core self-evaluation of high school students to improve the mental health and reduce the mobile phone dependence.