In order to improve the compactness and integration of electro-hydrostatic equipment to meet their miniaturization, a new electro-hydrostatic actuator (EHA) scheme is proposed, and the working principle and feature are introduced. The physical model of EHA is developed, numerical studies have been done to investigate the static and dynamic performances including the output force-pressure characteristics, the output speed-flow rate relationship, the load capacity and the dynamic response. The results show that: (1) the output force of the actuator is proportional to the working pressure and the output speed is proportional to the flow rate. (2) the EHA has a better load capacity, and the maximum output force is around 3720 N. (3) under a rated load of 3000N, the EHA has good dynamic performances with a rise time of 0.056s, an overshoot of 1.63% and a transient time of 0.17s. (4) the EHA can respond quickly and realize precise positioning. (5) the response time is related to the load, the pump displacement and the actuator effective area. The research results provide a theoretical basis for the development of high power density and efficient EHAs.