Abstract: The welding of billets is a key technology in endless rolling process.Flash butt welding machine in endless rolling technology was introduced including welding process, power supply system, control sy stem, hydraulic system and walking control algorithm of travelling mechanism.Welding power supply system adopts three-phase secondary rectifier circuit.Billets welding criterion is controlled by voltage feedback.Because billets welding is finished in dynamic process, the travell of welding machine is controlled by PLC.Welding hydraulic system is made up of clamping cylinder, tilting cylinder, upsetting cylinder and trimming cylinder, which can clamp billets, trim burr and so on.The whole design can meet the requirements of billets welding in endless rolling technology.