A membrane seawater desalination pressurization and energy recovery integrated method. Piston rods of single-rod piston-type seawater cylinders are connected with single-rod piston-type hydraulic cylinders to form two or more than two working combined bodies which operate alternately. In a process that the hydraulic cylinders drive the seawater cylinders to move back and forth, one piston cavity of a seawater cylinder sucks high pressure condensed brine in the process of moving forward and drains the high pressure condensed brine in the returning process; and the other piston cavity of the seawater cylinder sucks raw seawater in the returning process, pressurizes the raw seawater in the process of moving forward and continuously and stably outputs the pressurized high pressure raw seawater to a reverse osmosis membrane module. Meanwhile, a membrane seawater desalination pressurization and energy recovery integrated device is further disclosed.