The present disclosure provides a collimating backlight module, a preparation method thereof and a display device. The method for preparing the collimating backlight module includes: providing a light guide plate; forming a protective layer on a light emitting side of the light guide plate, where the protective layer simultaneously covers a light emitting area and a non-light emitting area of the light emitting side, a hollow area is formed on the protective layer, to expose the light emitting area of the light guide plate; and forming a light taking grating on the light emitting area of the light guide plate.