Evaluation method of part flatness error based on minimum area

The invention discloses an evaluation method of a part flatness error based on a minimum area method. The evaluation method comprises the steps of measuring and obtaining coordinates of measuring points on a measured plane, giving an initial parameter of the plane, enquiring the measuring points contacted with an error containing area according to the distances from the points to the plane, projecting the measuring points into a designated plane and converting into straightness error calculation in the designated plane by a coordinate system transformation method according to the quantity and the relative positions of the contact points, searching the measuring points contacted with the containing area and satisfying a straightness error discretion rule through the rotation change of the containing area in the projection plane, obtaining a rotated containing area, redefining a projection plane, conducting iterative calculation sequentially according to the straightness error calculation till a flatness discretion rule is satisfied, and outputting the flatness error and an optimal value corresponding to an ideal plane parameter. With the adoption of the evaluation method, the flatness error satisfying a minimum area discretion rule can be accurately calculated.