The automatic welding machine is designed to weld plastic materials. The automatic welding machine can weld advertising inkjet fabric, inkjet cloth, light box cloth, thick PVC cloth, mesh cloth, tarpaulin and other PVC, PE, DHPE, LDPE, EVA, Pp plastic materials that can be hot melted. It is small, light and easy to operate. It is equipped with temperature feedback sensor. The sensor can always monitoring the temperature of the outlet to keep a constant temperature. It uses advanced PID control technology, and adjust the power to make the temperature more constant automatically，the fluctuation is within 1 degrees. This function can make the welding result stronger. It also can avoid leakage. This machine is more suited to fast welding of large roofs