An adjustable flat-type cooling device includes a flat-type cooling fan assembly, two X-directional adjusting feet symmetrically located at two lateral sides of the cooling fan assembly, and two Y-directional supporting feet slidably received in each of the two X-directional adjusting feet. The X-directional adjusting feet and the Y-directional supporting feet together define a bottom surface for bearing against a horizontal supporting surface, and a top surface for a heat-producing apparatus to rest thereon. The cooling fan assembly could be adjusted to a position closest to a heat source of the heat-producing apparatus by pulling the X-directional adjusting feet and the Y-directional supporting feet to different extended positions; so as to provide best cooling effect. The adjustable flat-type cooling device requires only one cooling fan and therefore has an effectively reduced manufacturing cost.