Cast-in-place pile construction pile casing, construction method and cast-in-place pile formed through method

The invention discloses a cast-in-place pile construction pile casing, a construction method and a cast-in-place pile formed through the method, the pile casing comprises two arc-shaped steel plates and two V-shaped steel plates, the straight edges of the arc-shaped steel plates are welded to the bottom edges of the corresponding corners of the two V-shaped steel plates respectively, and the two V-shaped steel plates are oppositely located on the outer sides of the arc surfaces of the two arc-shaped steel plates to define a barrel wing-shaped steel pile casing; when the pile casing is erected, horizontal projections of the two arc-shaped steel plates are concyclic, the radius of the two arc-shaped steel plates is the same as that of a designed cast-in-place pile body, and the arc-shaped steel plates and the V-shaped steel plates are symmetrically arranged. Triangular steel plates are hinged to the side edges of the two corners of the lower end of the V-shaped steel plate correspondingly, can be rotationally c