The hydraulic bending machine includes a support, a workbench and a clamping plate. The workbench is placed on the support. The workbench is composed of a base and a pressing plate. The base is connected to the clamping plate through a hinge. The base is composed of a housing, a coil and a cover. It is placed in the recess of the seat shell, and the top of the recess is covered with a cover plate.