A centrifugal compressor and a refrigerating device. The centrifugal compressor includes: a shell, which has a fluid inlet and a fluid outlet; a motor assembly including a stator and a rotor, the rotor including a vertically arranged rotor shaft; a centrifugal compression mechanism, an impeller of which is connected with the rotor shaft so as to be driven by the motor assembly, wherein the centrifugal compression mechanism is arranged downstream of the fluid inlet to receive fluid, compress and pressurize the fluid, and output the pressurized fluid in a direction away from the motor assembly; and a guide member, which receives the pressurized fluid from the centrifugal compression mechanism, and which defines a flow passage alone or together with a part of the shell, wherein the flow passage is configured such that the pressurized fluid from the centrifugal compression mechanism passes through and cools the motor assembly.