To automatically import the BPA grid model to DIgSILENT/PowerFactory and improve the efficiency of large power grid modeling in DIgSILENT, this paper analyzes the mathematical model of the primary equipment and gives the conversion formula of model parameters between these two simulation software, studies the functions and technical characteristics of DGS interface and DPL programming language provided by DIgSILENT, summarizes the work steps for the BPA grid model imported to DIgSILENT, identifies the VC6 and DPL combining technical implementation and designs the overall structure, function and process of the tool software which is used to import BPA grid model to DIgSILENT, then develops this tool software. At last, this paper uses 3-machine 9-bus system and the equivalent system of the Beijing grid to test the tool software. By comparing the model parameters and power flow calculation results of the primary equipment in BPA and DIgSILENT, this tool software is proved to meet the design requirement.