The invention discloses a backlight module and a manufacturing method thereof. The backlight module includes a light guide plate and a light shielding plate. The light guide plate is located under a plurality of key caps and is provided with a scattering structure, and the scattering structure is located below the key caps. The light shielding plate is provided with a light shielding plate body, alight shielding part, a plurality of light exposing parts, a circuit and a light shielding plate light emitting element, the light shielding part and the light exposing parts are located on the side,close to the multiple key caps, of the light shielding plate body, and the circuit and the light shielding plate light emitting element are located on the side, away from the multiple key caps, of the light shielding plate body. The circuit provides electrical energy to the light shielding plate light emitting element, and the light shielding plate light emitting element emits light to the lightguide plate. The backlight module optionally arranges a light source in the light shielding plate or a reflection plate to enables the backlight module not to be needed to be internally provided witha light source circuit board, can further choose the light guide plate of the backlight module to combine the function of the reflection plate to enables the backlight module not to be needed to be internally provided with the reflection plate, and the backlight module can reduce the number of components to reduce the thickness and conforms to the requirements of the industry for the lighting andthinning of the backlight module.