Energy recovery device(ERD)is one of the crucial equipments of the reverse osmosis seawater desalination system.According to the practical application situation of the reverse osmosis seawater desalination system,a differential reverse osmosis energy recovery device with a function of pressure boost was developed.The test shows that this energy recovery device operates steadily and meets the use requirement of reverse osmosis system,and the effective energy recovery rate of the device can reach 96.3%.