Diffuser for a centrifugal compressor and centrifugal compressor having the same

A diffuser for a centrifugal compressor and a centrifugal compressor having the same. The diffuser (100) comprises a drive component (110), a transmission assembly (120), an adjustment assembly (130), a spool valve assembly (140) and a rear wall (150); wherein the transmission assembly is used for transmitting power produced by the drive component to the adjustment assembly, the adjustment assembly is capable of circumferentially reciprocating with respect to the rear wall and driving the spool valve assembly to reciprocate axially; and wherein a rolling element (160) is provided between the adjustment assembly and the rear wall. Intervention of a mechanism for adjusting a flow passage width is better achieved by such an arrangement in combination with an existing configuration of the diffuser; and a low-friction fit between the adjustment assembly and the rear wall is achieved by the rolling element.