Abstract: Due to the variability and low capacity factor of wind power, it is inevitable that wind power should be transmitted with thermal power through high-voltage transmission lines to the load centers. In this situation, the paper presents a method for power-transmission curve of wind power transmitted with thermal power considering wind power peak load regulation requirement. The peak load regulation requirement probabilistic model for transmitted wind power is proposed due to its random nature. Then, the optimization model for co-operation wind power and thermal power is presented, and the objective function being maximized is the transmitted energy The case studies are carried out for a system, and the results verify the effectiveness of the presented method