A model for resource provision policy in multi-unit maintenance program is developed. The model is based on integrated System Dynamics modelling methodology. 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 scheme then is transformed into the suggested research model. In the modelling process, emphasis is placed on resourcing strategy for maintenance involving human and procurement of spares and any other materials. The model is composed of three sub-models that interact based on causal loop modelling between variables. The human resource sub-model focuses on policies related to provision and management. The procurement sub-model takes into account all critical spare parts, tools and equipments, and any other supporting material. The interaction between variables with sub-models is then evolved into a multi-unit maintenance resource provision model. The developed system dynamics model has been verified using data from a case study. 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.