A valid scheme for power supply system intelligent upgrade was to pull a core monitor device into the system and making it to support IEC 61850. The scheme was introduced from two aspects, including the power supply system IEC 61850 information modeling and the MMS communication protocol conversion of the system SCADA information. In the information modeling, physical devices of the power supply system were mapped to logical devices, SCADA data were mapped to the instantiations of the compatible logical node classes, and the communication control mechanism was mapped to the report model. Communication protocol conversion mainly talked about the SCADA share mechanism between MMS and legacy communication protocols, including the shared memory, data storage format and the addressing algorithm. The practical test shows that the scheme could satisfy the requirement of power supply system intelligent upgrade.