The invention discloses a method for implementing lossless mapping of a 61850Ed2.0SCL model and a 61970CIM model on the basis of expanding the 61970CIM model. The method comprises the main steps of: electrical equipment container model mapping, non-electric function (sub function) model mapping, conducting equipment model mapping, universal equipment model mapping, topological relationship mapping, intelligent electronic equipment mapping, primary and secondary equipment association establishment, intelligent electronic equipment logic node mapping, and intelligent electronic equipment measurement mapping. The method implements complete mapping of the SCL model and the CIM model so as to fulfill the aim of lossless conversion of SCL and CIM. Mapping of the SCL and CIM models is implemented in a mode of expanding the CIM model, a main body structure of the CIM model is not modified and changed, and information is attached to the CIM model only in a conversion and expansion mode. Therefore, modification impact to an existing operating system based on the CIM model is also greatly reduced, and influence on system operation is reduced.