Traditional pump-controlled differential cylinder technology has problems such as complex hydraulic circuit, slow response and high energy consumption. Based on this, a combined control method of displacement and speed was proposed to directly control the differential hydraulic cylinder by using a variable servo pump. Firstly, differential cylinder combined control system was divided into three subsystems based on theoretical analysis of pump-controlled differential cylinder principle. Secondly, the model of the system in which the inner-loop controlled displacement and outer-loop controlled speed was established for simulation. Response speed under hybrid control had better dynamic characteristic than that under constant speed. Thirdly, the test platform was set up for experimental analysis of pump-controlled differential cylinder. The dynamic response of differential cylinder controlled by the system in which the inner-loop controlled displacement and outer-loop controlled speed was faster than that controlled by the system of constant speed, which reduced the time by 13.4%. Under constant pressure mode, the input energy consumption of serve motor was measured. After comparative experiments under different speeds and pressures, the system energy consumption under low speed and large displacement was decreased by 3kW. Simulation and experiment results showed that the response speed of pump-controlled differential cylinder was improved and the energy consumption was reduced effectively under the combined control mode of displacement and speed.