Abstract: A display device and its back light module and support column are disclosed. A display device includes a display panel and a back light module. The back light module includes a bottom casing, a plurality of light-emitting components located within the bottom casing and a plurality of support columns located within the bottom casing. Each support column is positioned between adjacent ones of the light-emitting components. Each support column includes a tapered member and a plurality of light-guide members. The tapered member includes at least two opposite surfaces, and the light-guide members are arranged on at least one of the two opposite surfaces, and each light-guide member protrudes from a corresponding one of the two opposite surfaces.