A backlight module, a method of manufacturing the backlight module, a display device and an illuminating device are disclosed. The backlight module includes: a light guide plate having a first surface and a second surface opposed to each other and at least one side surface between the first surface and the second surface, the side surface being provided with a first light reflecting structure and having an acute angle with respect to the first surface; a light source disposed at a side of the first surface, an orthographic projection of the light source onto the first surface being at an edge portion of the first surface adjacent to the side surface, wherein the light emitted by the light source is at least partially reflected by the first light reflecting structure after entering the light guide plate through the first surface of the light guide plate.