Digital simulation is usually utilized to analyze the operating characteristics of large-scale power grid, including electromechanical transient simulation for research on grid overall stability and electromagnetic transient simulation for study of local grid dynamic characteristics such as overvoltage calculation, protection configuration and DC power electronic switching device characteristics. However, power system data is mainly record as electromechanical transient simulation format and electromagnetic transient simulation data is quite poor. Therefore electromechanical transient data needs to be converted to electromagnetic transient data. For common model in PSASP and PSCAD software (such as generator, transformer, transmission line, load and compensator, etc.), this paper transform the model after comparing parameters using mathematical equivalence, and fully proves the feasibility of transformation to the PSCAD PSASP model through mathematics analysis.