Abstract: In this paper, a welding technology optimizing system of low alloy steel has been designed with Borland C⁺⁺ language.The system concerns three kinds of welding technology methods、twelve kinds of low alloy steels and many kinds of welding consumables.Having used C-Worthy as menu constructor,the system has color windows and menus which can be controlled by both hot keys and mouse buttons freely.Having applied reasoning technology combined forward with backward, user's target may be displayed gradually through a set of color windows and menus.With better portability,the system which exports its results on CRT or printer,also can be execut in any kinds of X86-PC computer or its compatable one.