Angularity is an important parameter to evaluate the position precision. According the new generation of GPS, a new method of evaluating plane to plane angularity error based on coordinate rotation was proposed. In the process of evaluation, first the datum plane is associated by the minimum zone method; and then the datum plane is transformed into the ideal coordinate system plane. Based on the ideal datum, the plane is obtained by coordinate rotation; angularity error value is the maximum distance subtracts the minimum distance that measured points to the plane. The measurement for a V-groove in arbitrary position is performed on a three dimensional coordinates measuring machine; the result shows that angularity error can be evaluated effectually and accurately using this algorithm.