The machine applies to welding for plastic door and window, It can weld many shapes and their intercombination, 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.