Abstract: The possibility and advantages of CAD technology for arc welding power source based on web platform were discussed. In regards of arc welding inverter power supply, the general scheme, design principles and concrete design method of the CAD system were proposed. A networked CAD system with common web browser as the client’s terminal was developed, which adopts the structure of browser, web server and database server. It was mainly based on the ASP dynamic server page technology and implemented by combining the ActiveX component, VB programming method and access database programming technology together. The results indicated that the system could work properly and the CAD procedure was completed. Given the information of the design conditions, the one-stop and multi-steps design of arc welding inverter power supply could be realized separately, including the calculation of all parameters and the selection of main components. The study would be helpful to the normalization, standardization and optimization of arc welding power supply design, as well as the quality improvement of products.