For the purpose of economy， it is necessary to optimize generation scheduling schemes with longer time-scale by monthly unit commitment. Based on the development of Jiangsu power grid， a methodology for coordination of monthly， daily and real-time generation scheduling is presented. Then the framework and a detailed calculation procedure of monthly unit commitment are developed. Meanwhile， the merits of monthly unit commitment are described. The results in Jiangsu power grid show that the unit commitment schemes can be effectively improved.