The CCHP micro-grid has advantages of high efficiency pollution,low power consumption,it has broad application prospects.In order to make the CCHP micro-grid system can be a reliable,safe,economical operaion,The first consideration to make full use of new energy sources,secondly to combine the use of restraint and storage factors.In this paper,a mathematical model on the economical operation of the micro-grid system with CCHPs in grid-connected operation are established.The given cost function takes into account the operation and maintenance costs,fuel consumption cost of the distributed generators and the power purchase or sale fees.Finally,an example analysis with improved particle swarm optimization is made based on the data of a neighborhood,and the validity and practicability of the method is fully demonstrated.