This research emphasizes at how do organizational cultures, cognition of organizational changes and personality traits influence employees’ organizational commitment. By literature exploring and using empirical survey methods with the Chunghwa Post Company Employees, we investigate factors that affect the organizational commitment, and various relationships among demographic variables, organizational commitment and other variables. This research enhances the management unit ability of increasing employees’ organizational commitment for organizational commitment is very important today. This research adopts the convenient questionnaire survey and the samples are employees of Chunghwa Post Corporation. The valid samples are 281 employees. After factor analysis and cluster analysis, we divide organizational culture into two groups “Organic-type culture” and “Mechanical-type culture”, and cognition of organizational changes into two groups “high cognitive organizational change” and “low cognitive organizational change”, and we also divide personality traits into two groups “social type” and “sensitive”. The main results showed as follows: 1.There are significant differences in organizational commitment of the employees by different organizational culture, organizational change cognition and personality characteristics. 2.Organizational culture, organizational change cognitive and personality traits of employees causes significant impacts on organizational commitment. 3.Employees with different demographic variables will have differences in the organization culture, organizational change cognition, personality traits and organizational commitment.