The invention relates to a mounting unit with a mounting part and a welding part and a method for making the mounting unit. The mounting part is provided with a mounting face and an outer side which is away from the face, the mounting part fixed to a matching face of a main structure is made of a material which cannot be welded with the main structure, and the welding part is fixed in a through hole of the mounting part. The welding part is a disc which is provided with a circumferential face, an outer end face being away from the mounting face and an inner end face being away from the outer side, and the shape of the welding part is consistent with that of the cross section of the through hole, and the thickness of the welding part is at least equal to that of the mounting part in the edge area of the through hole; the edge area of the inner end face of the welding part is provided with a circular groove, the welding part which limits the circular groove outwards in the radial direction forms a first shape matching part which extends outwards in the radial direction, and the welding part is connected to the mounting face through the first shape matching part and is fixed in the through hole; the central area of the inner end face of the circular groove in the radial direction serves as a welding face, and the welding part is welded on the matching face of the main structure; and the central area is aligned to the edge of a mounting side hole or protrudes from the the edge of a mounting side hole according to the standard, and the central area is aligned to the first shape matching part or protrudes from the first shape matching part.