Ultrasonically welding of 12 滋m PET/30 滋m PE laminated films were investigated in this paper. The
results show that the welding vibration amplitude has little effect on the welded joint strength of the laminated films when it varies between 2-10 滋m. The maximum welded joint strength appears when the welding vibration amplitude is 4-7 滋m. The welded joint strength increases first and decreases lately follow the increase of the welding time and welding pressure. The welded joint strength of PET/ PE is related to its crystal degree. When the welding time, welding pressure and the vibration amplitude increase, the crystal degree in the welding zone decreases first and then in creases, the welded joint strength increases first and decreases then. The PET/ PE welded joints show a wider melting
area and an accidented fracture surface and characteristics of tough fracture.