The invention discloses a lower die base of a bending machine. A plurality of oil cylinders are arranged in the entire lower die base and are communicated with each other in series through at least one oil pipe; and the plurality of oil cylinders and the oil pipe are filled with hydraulic oil. According to a hydraulic principle in a bending machining process of a workpiece, the hydraulic oil at any oil cylinder pressurizing position (high pressure position) of the entire lower die base can be forced to flow to a non-oil cylinder pressurizing position (weak pressure position) through an oil path so as to compensate and pressurize the non-oil cylinder pressurizing position, thus uniform compression of the entire lower die base in the bending machining process is ensured and the bending processing quality of the workpiece is further enhanced. Furthermore, the lower die base has a simple structure and can be suitable for the bending machines of any model.