Abstract: Having cast away the empirical design model, the authors have developed a software system for the computer-aided design of covered electrodes. This system, strong in versatility and good. for multi-purpose, is able to scientifically lay out the testing project, establish the mathematical model, optimize the formation of electrode covering, predict the mechanical properties of the weld metal, and trace out curves showing the relationship between the chemical compositions and the mechanical properties. Besides, the system possesses a data base. This system is characterized by its high quality in design results and convenience in operation. In support of this software system, a high-toughness covered electrode of the 686 MPa level for HSLA steels has been developed. The Charpy impact value of the weld metal reads up to 78 J at-50℃.