The present application provides a polarizer, a display module and a method of processing a polarizer. The polarizer is made of stretchable materials and shaped to be a curved surface by a hat pressing process. Along a light emission direction, the polarizer includes a polarizing functional layer, configured to convert light passing through the polarizing functional layer from natural light into linearly polarized light; and a protective layer, configured to protect the polarizing functional layer. The display module includes a flexible display, the polarizer and a curved cover which are stacked sequentially along the light emission direction. The method of processing a polarizer includes: placing a polarizer to be processed on a curved surface profiling stage; and shaping the polarizer to be a curved surface corresponding to a shape of the curved surface profiling stage by a hot pressing process.