Abstract: The research and development of calculate software on Traction Power Supply System were based on VC + + platform, which was adopted ActiveX Automation technology for secondary development of AutoCAD, to make the VC++ interface for AutoCAD drawing control, calculate all kinds of lines, all kinds of traction transformer connection form, all kinds of traction network power supply mode and various technical indicators calculation of the traction power supply scheme. Combined with abundant interface, efficient execution efficiency, strong ability of the underlying data exchange and combine the AutoCAD powerful graphics functions, the efficiency and quality of engineering design were improved.