The study aimed to investigate the use of health services by people with mental disorders and the influencing factors which were relevant to their use. The subjects were people with mental disorders in psychiatric rehabilitation institutions. Stratified cluster sampling was adopted in the study, and 333 samples were obtained from totally 19 institutions in Taoyuan, Taichung, Tainan and Kaohsiung. The tool of data collection was a self- made questionnaire. The SPSS 20.0 statistical software was adopted for conducting descriptive statistics, independent samples t-test, the calculation of Pearson correlation coefficient and regression analysis. The study results showed that: 1) Five personal factors, which were employment, educational attainment, degree of disabilities, the age of a subject when he/she received medical treatment and the age of a subject when he/she received psychiatric rehabilitation service, were predictive of the health service use of people with mental disorders. 2) Two influencing factors, which were sleep and the number of chronic diseases, were predictive of the health service use of people with mental disorders. 3) The health service usage behaviors of people with mental disorders had time-varying characteristics, and the service history can be measured by variables such as service items, frequency of returns and period of service use. At the end of the study, suggestions for promoting mental health education, connecting psychiatric rehabilitation institutions to the long-term care resources in communities, developing a good sleep environment and future research were respectively proposed.