The fatigue life is a major issue of weld joints due to a severe thermal exposure during the welding process. Welded joints experience highly localized heating and cooling from welding processes. As a result, the material properties around the welding joints can be in significant variations after welding. The prediction of fatigue life and crack propagation in welding parts of pouch cell type lithium polymer battery is the main objectives of this study. The series spot welding and laser welding processes between different electrode materials (Cu and Al) were virtually processed using a finite element method and validated against the metallography of welding specimen.