The invention relates to a 1000 MW thermal power unit booster pump comprising a bearing chamber, a cooling chamber, a main shaft and impellers. The main shaft penetrates the bearing chamber, and is connected to the cooling chamber through a mechanical seal, and the impellers are fixedly installed at the middle part of the main shaft; the booster pump further comprises two removable end covers anda U-shaped pump shell unit; during installation, the two end covers are symmetrically installed on the both sides of the bearing chamber, and a line connecting the centers of the two end covers is perpendicular to the main shaft; and the two ends of the pump shell unit are fixedly connected to the two end covers separately. Compared with the prior art, the booster pump is of great significance inensuring the sealing effect of the sealing face, saving the pump maintenance time, improving the working efficiency of the pump maintenance, saving the operating cost of a power plant, meanwhile, prolonging the service life of the pump and ensuring the long-time stable operation of a power plant unit through design of a new booster pump subdivision sealing structure and by adopting O-rings.