In order to enhance competence of companies , flexible human resource strategies have become more and more important in many companies as well as in hospitals. Hospitals now focused in decreased cost to improve profit and maintain their high quality of medical treatment. Flexible nursing manpower has become the main human resource strategy used in hospitals. This study focuses to investigate different working status nursing staffs in hospitals and analysis their organizational commitment , professional commitment and work performance . The critical findings of this study are as follows 1. Different demographic characteristics of nursing staffs have significant difference in organizational commitment , professional commitment and work performance. 2. Different working status nursing staffs in organizational commitment and professional commitment are different but not significant. 3. With the same working status of nursing staffs, they have stronger professional commitment than organizational one. 4. Formal nursing staffs have stronger organizational citizenship behavior than contingent ones. 5. The correlation shows that organizational commitment and professional commitment of formal nursing staffs relates positively to their behaviors of work performance. Based on the findings of this study, suggestions are made at two levels¡GThe hospitals and future research. For the hospitals , enhancing organizational and professional commitment of nursing staffs is good at their behaviors of work performance. Besides , if hospital can rearrange work tasks , it is good idea to use contingent nursing staffs to reduce manpower cost of hospital. For the future researches , they can compare behaviors among different industries and different professional areas.