The present disclosure is directed to a polishing head for polishing a wafer by a slurry. The polishing head includes a main body and at least two air modules. The main body has a cavity for accommodating the wafer, a main channel, and at least two sub-channels connected to the main channel. The at least two air modules are disposed at an outer surface of the main body. Each of the air modules is respectively connected to one of the sub-channels of the main body and configured to generate an air stream. When the polishing head rotates, the air stream forms an air curtain around the outer surface of the main body.