The Spearman′s correlation coefficients between various fabrication errors and functionalities were analyzed on a 3-belt phase-only pupil-filter. Three kinds of pupil-filters with different numbers of belts were compared to identify the influence of eccentricities of different belts. The correlation coefficients between eccentricity and the radius at half central intensity and Strehl ratio are both greater than 0.8,and rounding can cause the intensity of the first order sidelobe changing up to 29.04%,thus these two parameters are identified as the significant geometrical parameters. Besides,the eccentricities of outer belts affect the super-resolution performance more significantly than inner belts,therefore they need to be controlled with tighter tolerances. This method provides a theoretical foundation and a versatile technical route for the effective specification in design and manufacturing of micro-optical elements.