Based on IEC 61850 and IEC 61970, a power grid modeling strategy is presented to make transition from concentrated modeling for main control center to reference substation model on demand by different control centers. Then it solves on-demand sharing of grid model, substations wiring diagram and measuring information between smart substations and control centers at all levels, and among control centers at all levels. The research result has been applied to Suzhous 500 kV Changshu smart substation and smart grid dispatching technology support system pilot projects.