The invention belongs to the field of precision metering and computer application and discloses a method for evaluating a part by combining an entity gauge with measurement data in a
mathematical model form, and relates to a quick, stable, simple-form and digital method for evaluating straightness in a given plane, which comprises the following steps of: step 1, acquiring a
measurement point set,and establishing a boundary element set and a state element set according to the
measurement point set; step 2, establishing a feature
row vector set according to the measuring
point set and the corresponding normal vector; step 3, adding a key point; step 4, establishing an analysis matrix and an analysis
column vector; step 5,
rank analysis is performed on the analysis matrix and the augmented analysis matrix so as to determine whether optimization continues to be performed, key points are eliminated or a program is terminated; step 6, calculating an optimization direction; step 7, solving anew key point by using a chasing problem, performing optimization step calculation, updating according to the formula in the step 1, and entering the next cycle; or entering the next cycle accordingto the step 4; and step 8, terminating the program and obtaining an optimal value.