The present invention discloses a back light module and a liquid crystal display (LCD) device. A back light module comprises a light guide plate; both sides of the light guide plate are respectively provided with multiple notches; the back light module is provided with riveted nut studs in the notches; and buffer parts are arranged between the riveted nut studs and the notches. In the present invention, because buffer material such as silicone, rubber and the like is arranged between each notch and each riveted nut stud of light guide plate, the buffer material can provide effective buffer function when the light guide plat is affected by impact force to avoid damage caused by direct impact between the light guide plate and the riveted nut studs. Thus, low cost is achieved because of simple process and economic material. In addition, the tight contact of the light guide plate and the riveted nut stud is kept by the buffer part, and the shake of the light guide plate is avoided.