With the decrease of the fossil energy sources and increase of insecure factors of large-scale power grid， distributed generation technologies gain more and more attentions. According to the characteristics of distributed generations， a new model of unit commitment with the objective of minimizing generating cost is proposed. A dispatch strategy is proposed to handle the unit commitment problem of distributed generation systems with multiple energy sources. The proposed unit commitment model considers both traditional constraints and special constraints related with distributed generation systems. This unit commitment problem is solved by an improved genetic algorithm. A relevant example verified the efficiency of the proposed model and algorithm.