In the era of mass production, bulk and individual customizing is the ultimate purpose of the clothing processing. Now, how to make the customized body dimensions generated automatically is the foundation of Agile Manufacturing. The allowance of clothes can be provided according to the style and size of the clothing, and the function of mapping the human dimensions to measurements is a part of The Clothing CAD system .This paper introduced the detail of design and implement on the demand of the system which is made up of two parts. The first part of the system can classify the body dimensions according to diffferent criteria; when the body dimensions and the clothing style are fixed ,the second part will search in the Expert Knowledge database, and finally, the most optimalizing allowance of clothes is given. With this system, personalized customization of garment will come true under the condition of volume-produce; it will not only improves the efficiency, but also increases the accuracy of the customization.