Abstract: In order to ensure welding strength of QU120 crane rail on vertical transfer track of a project,gas pressure welding technology was studied and gas pressure welding technology and technical conditions of QU120 crane rail were formed. Welding testing standard of QU120 crane rail was established and welding performance was evaluated from aspects of ultrasonic testing,mechanical properties,metallographic structure,drop weight test and so on. Test results of 8 groups of specimens showed that tensile strength of welds was better than that of base metal,and other properties met requirements of test standards. The research results had been applied to 706 joints,which effectively eliminated quality defects and had advantages of high efficiency and high accuracy. Safety,reliability,smoothness and bearing capacity of the vertical transfer track had met requirements of the mission since it was put into use for five years.