The invention provides a large-scale steam centrifugal compressor volute eliminating the secondary flow loss and a use method of the large-scale steam centrifugal compressor volute eliminating the secondary flow loss and belongs to the field of evaporation and concentration and power engineering. The large-scale steam centrifugal compressor volute eliminating the secondary flow loss is composed of a diffuser, a left deflector, a right deflector, a volute body and the like. Through the deflectors additionally arranged inside the volute body, the secondary flow loss formed in the flowing process of fluid in the volute is effectively reduced, and the pneumatic performance of the volute is improved; meanwhile, through series flow holes in the deflectors, and the flow loss caused by the fact that a boundary layer of each deflector is thickened is reduced; and in addition, the deflection, under the internal and external pressure difference inside a compressor, of the volute body is reduced, a supporting function on the volute body is achieved, and the possibility that an impeller scrubs a shell of the compressor is lowered. By the adoption of the large-scale steam centrifugal compressor volute eliminating the secondary flow loss and the use method of the large-scale steam centrifugal compressor volute eliminating the secondary flow loss, the flow loss of diffuser airflow in the volute is effectively reduced, the operation efficiency of the centrifugal compressor is improved, the safety of the negative-pressure operation centrifugal compressor is improved, and the large-scale steam centrifugal compressor volute eliminating the secondary flow loss meets the target of the national industrial energy conservation and emission reduction development strategy.