Precision machining method for large curved surface mold

The invention discloses a precision machining method of a large curved-surface mold. The method comprises the following steps of: performing forward and reverse rough machining on the large curved-surface mold on a numerical control milling machine; standing the large curved-surface mold in the air in a free state; finish machining the bottom plane of the die in a free state; turning over the mold, positioning by the bottom plane of the mold, and checking the flatness of the bottom plane of the mold body in a free state; preheating the machine tool, so that each moving part of the numerical control machine tool reaches a heat balance state in a machining area, and the machine tool is in a stable operation stage; verifying machine tool precision change; die large curved surface machining, wherein a semi-spherical blade is adopted for conducting finish machining on the large curved surface; and high-precision curved surface detection is carried out on the processed large curved surface. The method has the benef