The invention discloses a device for controlling an inclined-column reinforced skeleton and a protecting layer and a construction method, belonging to the field of the building construction. The device comprises a positioning reinforcing stirrup which is fixed on the inclined-column reinforced skeleton and two supporting mechanisms which are respectively arranged on the acute angle side and the obtuse angle side of the inclined-column reinforced skeleton, each supporting mechanism comprises a substrate which is fixedly connected with a framework beam main bar, a supporting plate which is tightly attached to the acute angle side surface or obtuse angle side surface of the inclined-column reinforced skeleton on the position of the positioning reinforcing stirrup and a supporting rod for connecting the substrate and the supporting plate. The construction method comprises the following steps: prefabricating the supporting mechanism; installing the supporting mechanism on the acute angle side of the inclined-column reinforced skeleton; installing the supporting mechanism on the obtuse angle side of the inclined-column reinforced skeleton; pouring the concrete, disassembling the supporting rod and the supporting plate to be recycled after the concrete is finally consolidated, wherein the substrate is used as an acting point for obliquely supporting the lower layer of inclined-column reinforced skeleton supporting plate. The device is simple, reliable, low in cost and rapid and convenient to construct.