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This paper designed the hydraulic CNC pipe bender with dieless forming technology and hydraulic servocontrol technology. The pipe bender can create variational pipe bending curve. It is controlled by computer. The hydraulic CNC pipe bender can work without mould. It has conquered the old method in machining the pipe of bus frame, which depend on aptotic mould formerly. This paper has expatiated the working principle of pipe bender and the forming principle of radian pipe track, and researched on controlling the shape of pipe section, designing control system, controlling and compensating of the spring-back of pipe bending etc. The new pipe bender can satisfy the request of manufacturing various bus frame, and improve efficiency of pipe bending obviously.