The invention relates to a long U-shaped tube bender, in particular to the long U-shaped tube bender capable of processing two tubes in different pipe diameters. The long U-shaped tube bender comprises a base, a stand, a rounding and straightening device, a feeding device, a cutting device, a feeding path, a bending device, a receiving device and a controller, wherein the rounding and straightening device comprises two sets of rounding and straightening mechanisms; the stand is provided with a position switching mechanism for adjusting positions of the two sets of rounding and straightening mechanisms; the feeding device comprises two kinds of feeding channels for conveying pipe fittings in different pipe diameters; a position switching part for adjusting the positions of the two feeding channels is arranged on the stand; the bending device comprises two kinds of bending channels for bending pipe fittings in different pipe diameters; and a bending bracket is arranged on the stand and is provided with a position switching part for adjusting the positions of the two bending channels. The long U-shaped tube bender has a simple and reasonable structure, is accurately positioned, is convenient to operate and easy for manufacture. On the basis of no dismount and replacement of main parts, the long U-shaped tube bender can be used for processing the pipes in different pipe diameters and has wide processing range.