The objective of this research is to develop the CAD system package used by personal computer for automatic pattern designs, grading, and nesting, based on the mathematical and computational principles. After accomplished the drawing of patterns and variations, this package excites the drawing of margins, marks, holes and notches. The margin designs are considered the methods of the sewing, textiles, and garments for using the textiles efficiently and maintaining the silhouette of garments. Marks and holes designs are automatically obtained from pattern designs steps and notches are divided on segments composed of each pattern by pursuit the paths. After accomplished the step of the drafting patterns, this CAD package excites the margin and mark programs, which organizies the sub-pattern data base. To develop the CAD system package used by the personal computer for automatic pattern designs and cutting systems, processing of apparel systems must be analyzed by the mathematical and computational principles. First of all grading is the step of magnification or reduction for variable sizes. This is automatically gained from original patterns. Then nesting means that employees arrange the patterns on textiles. The purpose of this step is minimizing the losses of textiles. This is easily accomplished by the transformation sub-programs, used to change the image on the display screen and to reposition the items in the pattern data base. This sub-program, which is applied to the pattern data in order to nest the minimum arrangement, is composed of translation, magnification, reduction, rotation and separation. Therefore, this CAD system package is the total procedures by which the sequence of processing steps to involve drafting clothing patterns, modifications, grading and nesting is planed and carried out, in the operation of this CAD package by the user, every programs is mutually joined. And user obtains the final output required as package activities increase.