The invention discloses a centrifugal compressor and a refrigeration system comprising the centrifugal compressor. The centrifugal compressor comprises a motor, at least one bearing assembly and at least one centrifugal impeller; the motor comprises a motor casing and a motor shaft at least partially arranged in the motor casing; the bearing assembly comprises a bearing block and at least one oilless rolling bearing; the bearing block is arranged on the motor casing, while the oilless rolling bearing is arranged on the bearing block and connected with the motor shaft in a sleeving matching manner; a refrigerant channel for supplying a refrigerant to the oilless rolling bearing is formed in the bearing block; the centrifugal impeller is arranged outside the motor casing and connected with the motor shaft so as to be driven by the motor shaft to rotate. According to the centrifugal compressor of the present invention, the oilless rolling bearing is employed to support the motor shaft and no lubricating oil thus is required, such that frictional loss between the motor shaft and the oilless rolling bearing is effectively reduced and the overall energy efficiency of the centrifugal compressor is improved.