Process change-oriented automatic three-dimensional process model updating method

The invention discloses a process change-oriented automatic three-dimensional process model updating method. The method comprises the following steps of: firstly obtaining machining features on a part model, and combining machining process information on the basis to construct machining elements; carrying out constrained relationship construction on the machining elements on the basis of geometric structure of the features and the process information, establishing a mutual constrained relationship matrix among the machining elements, and dividing the machining elements into modules which are not mutually influenced through line transformation and column transformation of the matrix, wherein only the machining elements in the modules are mutually influenced during process change effectiveness judgement, and the machining elements between the modules are not mutually influenced; carrying out change effectiveness judgement on the basis of a process change type so as to ensure the reasonability of the change; and