The increasing installation of wind farms in different countries has raised the importance of their reliability and availability. A basic solution for this issue is preventive maintenance, in which the shutdown arrangement of the turbines is scheduled so that the required power is provided without interruption. In this regard, two important goals must be considered simultaneously. First, maximizing the profits, and second, maintaining the reliability to an acceptable level. In this paper, a linear model is proposed for the wind farm preventive maintenance schedule which maximizes the wind farm profit and considers various constraints including reliability threshold, supply and demand, maintenance necessity, continuity, and duration, the allowable number of turbines in maintenance, priority and deadline, manpower and cranes availability, and so on. In the proposed model, the market price of electricity is included in the calculation of farm income, and some constraints are proposed for the first time. In addition, the uncertainty of wind farm generation is considered based on the Weibull wind speed distribution function and deterministic equivalencing method. The proposed linear model for preventive maintenance scheduling has been implemented on a wind farm with 50 units over a 52-week time horizon, and the results show that the power plant profit is maximized and the reliability is also maintained to an acceptable level.