Purpose To meet the demands of fast response and high power density in Electro-Hydrostatic Actuators (EHA), this study aims to develop a novel rectangular piston pump and carry out experimental investigations on its physical prototype. Design/methodology/approach The structure of the rectangular piston pump is designed, and the model of the core friction pairs is established. The rectangular pistons of this pump are arranged radially to reduce radial size and enhance suction capacity. To mitigate the negative impact of wear, wear reduction designs are used from the perspectives of structural optimization and surface strengthening. An experimental test platform is constructed to evaluate the pump’s performance. Findings Performance experiments validate the feasibility of the novel pump. The study highlights the importance of appropriate oil suction pressure to ensure efficient operation of the EHAs. Originality/value A novel rectangular piston pump is proposed and its feasibility is validated. Experimental studies on the performance of the pump provide technical support for its application in systems such as EHAs. Peer review The peer review history for this article is available at: Link to the cited website