Reciprocating-switcher energy recovery device (RS-ERD) can reduce the energy consumption in membrane desalination system for its high efficiency. However, the initial one-plate structure of the RS-ERD requires a large diameter in plates to ensure its basic capacity, which not only enlarges the switching load of water hydraulic actuator, but also causes a significant fluid fluctuation of the device during the stroke switching. To solve the problem, a modified RS-ERD with the pilot valve plates was designed and experimentally investigated in a SWRO desalination system. The experimental results illustrated that compared to the previous RS-ERD, the starting-up pressure for the new RS-ERD decreased by a half to be about 0.25 MPa, and 72.16% HP brine consumption for water hydraulic actuator was reduced in stroke switching. Thanks to the significant decrease in HP brine consumption, the pressure fluctuation amplitude in HP fluids was declined by 40% under the pressure of 6.00 MPa and the flow rate of 30m(3)/h. Meantime the new RS-ERD remains a competitive energy recovery efficiency of up to 98.50%. This paper provides a practical method to improve the working performance of RS-ERD.