When the military organization will be changed to fully volunteer force, voluntary servicemen and military organizations will become an employment relationship. It will be especially meaningful that understanding the perceptions, attitudes and behaviors of volunteer officers and staff. In this study, volunteer officers and members of a military school are as a sample to explore the relationship among psychological contract implementation, job involvement, role overload, and job performance. Basing on the effective dyad of 384 subordinates and immediate supervisor questionnaire, the study found that the volunteer officers' psychological contract implementation positively impacts job performance. In addition, the relationship will be partial mediated by job involvement. Besides, role overload moderates the relationship between job involvement and job performance. The role overload will decrease the relationship between job involvement and job performance. Based on the findings, this study suggests the management practices and researches in the future.