A backlight module includes a reflective plate, a light module and a heat dissipation module. The light module and the heat dissipation module are disposed at two sides of the reflective plate. The light module has a number of light emitting diodes to emit light. The heat dissipation module includes at least one heat pipe, a heat sink and a fan on an end of the heat sink. The heat pipes are disposed between the reflective plate and the heat sink to transfer the heat generated by the light module. The at least one heat pipe defines a number of nano-scale recesses in an inner surface thereof.