A System Dynamics model for resource provision policy in multi-unit maintenance program is developed. First, a scheme is developed to formulate and evaluate policies regarding the provision under uncertain condition or resource requirement in a period of planning to result in minimum maintenance cost. The model emphasizes on resourcing strategy involving human and procurement. It is composed of 3 sub-models presented in a causal loop modelling. The human resource sub-model focuses on policies related to provision and management. The procurement sub-model takes into account the procurement process and inventory system. Due to data availability, the verification has encloses only the relation between maintenance and human resources but further application on wide range of resources through case studies is intended. The advantage of this model is related to its wide outlook of interrelated variables of a complex multi-unit maintenance system. This model can show the impact of one decision in a certain maintenance resourcing system on the other maintenance resourcing system and will lead to an optimum policy for maintenance resource provision system.