Abstract There is no literature explores the relationship between manpower and performance of the Taiwan¡¦s psychiatric hospitals yet. This research takes samples from seven public psychiatric hospitals in Taiwan to investigate: 1. Performance measurement of psychiatric hospitals. 2. The influence of psychiatric hospitals¡¦ manpower inputs on service performance. The orientations of data analysis in this research are research framework and research hypotheses, and then collect data from seven domestic public psychiatric hospitals. According to the nature of gathered data, we applied SPSS software on Descriptive Statistics, Pearson Correlation Analysis, K-Means Cluster Analysis, and t-test for difference of two samples mean, to explore the relationship between manpower input and service performance. Research outcomes: 1¡BAlthough service items don¡¦t increase in high professional manpower structure compare to low professional manpower structure, the service amounts increased significantly. Test results show that the hypothesis 1-1 is not supported, but hypothesis 1-2 is supported. 2¡BGroups with higher manpower quality input have significant increasing in service items¡¦ performances, but not significant statistically. Even though groups with higher manpower quality increased service items, the service amounts do not raise. However, groups with lower manpower quality input have significant increasing in service amounts¡¦ performances. It means that the significantly negative correlation between manpower quality and service amounts¡¦ performances. Test results show the hypothesis 2-1 is not supported, neither is hypothesis 2-2. 3¡BEven though the service items¡¦ performances have no significant increasing in the groups with high formal and contracted personnel percentages input, the service amounts are increased significantly. Therefore, the difference of formal and contracted personnel percentages input has significant influence on service amounts. Test results show the hypothesis 3-1 is not supported, but hypothesis3-2 is supported. 4¡BPsychiatric hospitals with high manpower costs input do not increase service items, but increase service amounts. Test results show the hypothesis 4-1 is not supported, but hypothesis 4-2 is supported. ¡@The relationship between psychiatric hospital¡¦s manpower input and service performance is clearly realized through this research, which could be the reference for hospital managers to adjust profession manpower and to employ personnel in the future. Meanwhile, it can facilitate managers to control correct developments, to use every manpower portfolio engaging in medical operations, and to exert maximum efficiency of human resources with most economical manpower costs to improve psychiatric hospitals¡¦ service performances. ¡iKeywords¡j: Psychiatric hospital, Manpower input, Service performance