The invention discloses a construction method for forming a force body by combining an oblique steel pipe with cemented soil. The construction method comprises the following steps that a drilling machine is started, a drill rod drills into a soil body obliquely for hole forming, after specified depth is reached, the drill rod continues drilling, cement grout is jetted, and thus a segment of cemented soil enlarged body is formed; the drill rod is lifted away from a drilled hole, then the steel pipe is inserted into the cemented soil enlarged body along the drilled hole, and a plurality of grouting holes are distributed in the contact face of the end of the steel pipe and the cemented soil enlarged body; and supplementary grouting is conducted into the cemented soil enlarged body through the grouting holes in the steel pipe, and thus the steel pipe and the cemented soil enlarged body form an integrated structure. The construction method has the advantages that through oblique drilling of the drill rod and grout jetting, the uniform-size cemented soil enlarged body can be formed, the after-inserted steel pipe and the cemented soil enlarged body form stable connection through supplementary grouting, barb-shaped angle iron protection parts on the pipe wall and short ribs, and thus the integrated structure with high bearing capacity is formed.