Abstract: A light emission module and a light guide plate and a manufacturing method thereof are provided. The light guide plate is configured to guide the light received and has a first lateral surface and a tongue extending from the first lateral surface toward a light source. The tongue has a flat end surface that faces or engages with the light source. The light guide plate receives the light emitted from the light source by the flat end surface, so as to reduce or eliminate the gap between the light source and the light guide plate. Therefore, the loss of light energy during the light traveling in air is effectively reduced, and the intensity of light received by the light guide plate from the light source meets expectation, improving the lighting effect of the light emission module.