The machine applies to welding for plastic door and window , It can weld many shapes and their inter combination, it is PLC controlled and pneumatic drive. It has the characteristics of high automation level, better reliability, wider working range, etc. its 4 working parts can work singly, synchronously or do combinational working. It can compose two-point welding machines to work. It adopts track, which makes its anchor points more accurate, better reliability and it has a longer life.