In higher education field, the discrepancies in promotion and salary between permanent staff and contract staff resulted in many issues like low organizational commitment, etc. To better understand the current situation of the contract staff, we investigated all the contract staff in Peking University using organizational commitment table. The results showed that: contract staff received high affective commitment, followed by normative commitment but the continuance commitment was low; personal market competitiveness and organizational support had significant effect on staff's organizational commitment; effective communication, fairness and reorganization of the department leader may affect staff's organizational commitment. The research suggested that organizational support was an important factor besides staff's personal market competitiveness