The utility model discloses a forged piece assembling and adjusting device which comprises a base and a vertical pipe structure vertically installed in the middle of the base, and the vertical pipe structure is sequentially provided with an adjusting nut, a lock nut and a loading platform from top to bottom. The vertical pipe structure comprises a primary casing pipe and a second casing pipe which is sleeved with the primary casing pipe. The periphery of the upper portion of the primary casing pipe is provided with a plurality of supporting plates, the upper portion of the secondary casing pipe is provided with an adjusting stud, and the carrying platform is arranged on the adjusting stud. The loading platform comprises a panel, a plurality of nuts are arranged on the positions along the diagonals of the bottom of the panel, the positions corresponding to the nuts are provided with installation holes, the nuts are connected with bolts in an assembling mode at the positions of the installation holes, and rubber pads are arranged at the joints of the bolts and the installation holes of the panel. The forged piece assembling and adjusting device is simple in structure, easy to operate, capable of conveniently adjusting the height and the levelness of forged pieces of various sizes and capable of ensuring the assembling effect of the forged pieces and a pipeline system of a straight pipe segment, capable of being used repeatedly and convenient to carry.