A support frame, a display device and mounting method thereof. The support frame includes a main body and a protrusion disposed at a side of the main body; the main body includes a first portion located on the protrusion and a second portion located under the protrusion, a thickness of the first portion is at least equal to a thickness of a touch cover plate; a thickness of the second portion is at least equal to a thickness of a backlight module; and a thickness of the protrusion is at least equal to a thickness of a display panel.