Marine LNG impeller triangular hole alignment tool and machining method

The embodiment of the invention discloses a marine LNG impeller triangular hole alignment tool and a machining method.The marine LNG impeller triangular hole alignment tool comprises a triangular shaft, an alignment part and an assembling part, in the using process, an impeller to be machined can be arranged on a workbench of a machine tool firstly; then, a triangular shaft of the marine LNG impeller triangular hole alignment tool is inserted into a triangular hole of the impeller to be machined; then the to-be-machined impeller is aligned through the marine LNG impeller triangular hole alignment tool; and finally, finish machining is conducted on the impeller to be machined on the basis of the alignment result, the machining precision can be guaranteed, the marine LNG impeller triangular hole alignment tool aims at solving the alignment problem existing in the machining and manufacturing process of a triangular hole transmission mechanism adopted by a marine LNG centrifugal compressor, the special tool is pr