To cope with the inefficient data collection of the power grid planning in multisectors and multilevels, the power grid planning and management decision support system based on CIM is designed and programmed. The database based on CIM model is designed as the underlying basis in the system, the database is regularly updated by the GIS system, marketing system and external introduction, and the data sharing is realized. The functional level is divided into evaluation and analysis module, planning module and data publishing module. Evaluation and analysis module mainly supports the evaluation of power supply capacity and operation level of power grid status; planning module mainly supports the auxiliary decision work and evaluation of the planning and design work; and data publishing module mainly supports the query function of the data issued in the above two modules. The system is verified to be reasonable and high efficient to the power grid planning work in a local distribution network.