Disclosed are a display module, a display device and a viewing-angle switching method. The display module includes a backlight module, a display panel, a lower polarizer sheet, a viewing-angle switching element and a transparent cover plate; the viewing-angle switching element and the transparent cover plate are arranged between the display panel and the lower polarizer sheet, and the transparent cover plate is arranged on a side of the viewing-angle switching element that is close to the lower polarizer sheet; the backlight module is configured to supply light that meets a preset condition, the viewing-angle switching element is configured to switch viewing-angle modes of the display module; the viewing-angle modes include; a first viewing-angle mode and a second viewing-angle mode; and a viewing-angle range of the first viewing-angle mode is smaller than a viewing angle range of the second viewing-angle mode.