The variable displacement hydraulic motor system (VDHMs) articulated in this article is a kind of volumetric control system, which has the characteristics of energy conservation, high efficiency, and high control flexibility. In order to meet the requirements of operating conditions on aircraft bay door, the mathematical model of VDHMs is built, the system feature of VDHMs is analyzed and a three-variable-control strategy with power limitation is proposed. The simulation results shows that the displacement of variable displacement hydraulic motor can be regulated rapidly and precisely under the proposed control strategy and the system has a good control performance and energy-saving effect.