The invention discloses a concrete slant component upper supporting system and a construction method for the same. The concrete slant component upper supporting system is built on a completed reinforced concrete slant component and comprises a plurality of concrete steps arranged on a slope of the reinforced concrete slant component; the slope of the reinforced concrete slant component is provided with anti-shearing slots and vertical insertion ribs cast with the concrete steps; each concrete step is provided with elongated I-shaped steel; a supporting rack is built over the I-shaped steel; and supporting stand columns of the supporting rack are supported on the I-shaped steel. With arrangements of the concrete steps and the increase of the I-shaped steel, concentrated force of the supporting rack can be converted into uniform-distribution force, so damage to a top plate surface layer can be eliminated; and a cross section of each stand column is evenly stressed, so perpendicularity can be guaranteed and local stability of the column member can be enhanced.