The invention discloses a rapid-replacement clamping tool. One end of a mandrel is provided with an installation hole. At least one axially extending long strip-shaped opening is formed in the side wall of the installation hole. The diameter of the end, facing the inner portion of the mandrel, of the long strip-shaped opening is smaller than that of the end, facing the outer surface of the mandrel, of the long strip-shaped opening. The mandrel is fixedly sleeved with an outer sleeve. A conical face is arranged on the inner side of the outer sleeve, wherein the inner diameter of one end of the conical face is smaller than that of the other end of the conical face. A pressing ring is inserted between the outer sleeve and the mandrel in an axially sliding mode. An elastic piece enables the pressing ring to always have the movement tendency of moving towards one end of the mandrel. A radial hole corresponding to the long strip-shaped opening in position is formed in the side wall of the pressing ring. A containing space is defined by the radial hole, the long strip-shaped opening in the mandrel and the conical face of the inner side of the outer sleeve. A ball can be exactly contained in the containing space. The side, facing the inner portion of the mandrel, of the ball can exactly extend into the installation hole formed in one end of the mandrel. The rapid-replacement clamping tool is simple in structure, not prone to damage and convenient and flexible to use and saves time and effort.