To satisfy the demand on graphic editing， data preparation and presentation of the power grid equipment in power grid economical operation， a service-oriented and B/S-based power grid diagram editing system is implemented by combining the latest Silverlight 2.0 and Windows communication foundation（WCF） technology. The user defined power grid equipment diagram controls and their editing functions are realized using the extensible application markup language（XAML） and C language. The server side applications are designed as a multi-layer architecture. The equipment diagram data is stored in SQL Server 2005. By calling the WCF service interface， client side Silverlight can realize graph and data communication with server side application using the HTTP protocol. The system has helped meet the need of the power grid enterprise， solving the data sharing problem in a multi-user environment while improving the efficiency of installation， deployment and maintenance of traditional C/S based graph system and enhancing the work efficiency of the enterprise.