Abstract: Locus figures of the point on the planetary gear distinguish regular from irregular figures and they all have corresponding application value. Basic relation of figure classification is got by setting up locus equation of the point on the planetary and letting one to three order differentials of one coordinate on one position all be zero. The design conditions of the regular polygons with the same side and regular polygons with the same angle and recurrence spiral with many rings and adjacent convolution with loop are put forward. It provides a theoretical basis for designing the regular figures and high order intermittent mechanisms at one limit position or two limit positions with a single stroke and many strokes.

Key words: computer application, figure classification, differential geometry, regular figure, planetary gear