The invention provides a multi-angle adjusting and clamping device for welding of a special-shaped pipe fitting. The multi-angle adjusting and clamping device comprises a bracket, a square rail and afixed gear, a set of sliding supporting seat is slidably connected with the upper end face of the bracket, a set of fixed chucks is connected with the right end face of the bracket in an axial mode, aset of middle gears is connected with the right end face of the bracket in an axial mode, a set of middle gears is connected with the left end face of each sliding supporting seat in an axial mode, aset of center rotating shafts is connected with the upper part of each sliding supporting seat in an axial mode, a set of adjusting pulling seats is slidably connected with each center rotating shaft, and a set of adjusting nuts is connected with the left end face of each adjusting pulling seat in an axial mode. Movable chucks and the fixed chucks are arranged to rotate synchronously, the fact that the welding seam cannot change is ensured, and the welding quality is improved; and by adapting rotating of the pipe fitting, welding is achieved through a overall non-rotating manner, blocking dueto the clamping device is avoided, secondary welding is avoided, one-time welding molding is achieved, and the welding quality is improved.