A new mixed-integer linear programming (MILP) model for maintenance scheduling optimization for wind farms is proposed. In the purposed problem, maintenance crew are allowed to perform the maintenance activities on known periodic interval times due to production plan, limited resource and logistics, harsh weather seasons, and so on. Logistic time for the transportation of groups of maintenance crew with the required tools and spare parts is considered that can be different from one team to another. Considering that working at height in adverse weather conditions threatens the safety of the maintenance crew and increases the hiring cost of skilled technicians, minimizing the completion time of the maintenance activities is of interest. Therefore, and taking into account the criticality of the maintenance activities of the teams, the objective of the presented model is to minimize the weighted completions time of the maintenance teams. The weights are determined according to the criticality of the modules which the maintenance crew are dealing with. To validate the presented model, a number of test problems are generated randomly and the results are discussed.