The invention discloses a centrifugal compressor for an isomerization device. The centrifugal compressor includes a spindle, impellers, separating plates, a shaft coupling, a diffuser, an upper casing, a lower casing, a sealing assembly and bearings; and the centrifugal compressor is characterized as follows: (1) the casing of the compressor is divided into the upper and lower casings from the horizontal plane of a rotating shaft, the upper casing is in fixation with the lower casing through sealing bodies on the two ends, and the lower casing is fixed on a support seat; and (2) a rotor is formed by installing the multi-stage backward-bending closed impellers, spacer bushes, balancing disks and other parts on the spindle in a series manner, and the rotor is placed on the lower casing through the bearings and bearing pedestals. The multi-stage backward-bending closed impellers adopt impellers with equal diameters; and the front of each grade impeller is provided with wheel cover seal, and the two ends of the compressor are provided with shaft end seal and dry gas seal structures. The centrifugal compressor is especially suitable for isomerization process in petrochemical industries,and good economic benefits can be obtained.