This paper deals a production and maintenance optimization problem for a wind turbine system in order to satisfy a random demand under given service level. A jointly optimization is made by combining between energy production and maintenance plan in order to establish an economical energy production planning and an optimal maintenance strategy according to the wind turbine degradation. The key of this study is to consider the influence of the energy production rate on the degradation degree of wind turbine. We prove simultaneously, with stochastic constraints of production and maintenance problem, an economical energy production plan and a maintenance planning which minimizes the average total cost of holding, production and maintenance. A numerical example is studied in order to apply the developed approach.