An exemplary backlight module (2) includes a light guide plate (21) and a light source (20). The light guide plate includes a body (211) and a protrusion (212) extending from the body. The body includes a light emitting surface (2111) and a side surface (2112) adjacent the light emitting surface. The light source includes a wire (22) which is disposed in a space defined between the side surface and the protrusion. The backlight module is compact with a reduced length.