Geometric error screw theory modeling method for numerically-controlled machine tool

The invention discloses a geometric error screw theory modeling method for a numerically-controlled machine tool. The method includes the first step of establishing an overall coordinate system R at any point on a machine body, establishing instant reference coordinate systems R' at reference points of the tail ends of a kinematic chains and establishing cojoined coordinate systems R[i] on kinematic pairs according to the kinematic chains of the numerically-controlled machine tool, and establishing a machine tool kinematic chain geometric error model containing location independent geometric errors and non-location independent geometric errors, the second step of obtaining a whole machine geometric error mapping model through the machine tool machine tool kinematic chain geometric error modeling method in the first step, and the third step of carrying out separation on compensable freedom degree geometric errors and non-compensable freedom degree geometric errors influencing the tail end of the complete machi