Abstract: As the complexity and difficulty to create and mesh modeling of welded joint inMsc.Marc' s preprocessing system, a feature database of welded joint for the kind of oil box was developed with Python language.Meanwhile a new menu system based on welded joint feature was also established withMarc' s menu languages.These improvements of feature database and menu system make numerical simulation of welding process easier and design of welded joint faster. In addition, this method also provides good guidance of adding user special program into Marc and applying Chinese patch to Marc.