According to the characteristics of the region grid,this paper applies the CBR (case-based reasoning) methods on the expert system of dispatching operation order,which can overcome the disadvantages of the traditional RBR (rule-based reasoning) system, such as complicated programming and difficulty to extend the knowledge base. The system can adapt the development of the region grid much better. This paper uses a strategy that calculates the similarity in two steps: first calculating the net similarity and then the substation similarity. Because the structure of the grid is considered, the accuracy of the system gets raised. CBR method is also adopted to design the preview of the order and the error prevention which realizes the modularization preview. The system can adapt the characteristics of the region grid which can lighten the operators’ burden.