The purpose of this study was to provide some preliminary results on application of 3D scan data of head shapes to the hat design and pattern-making. This paper defined necessary measurement items and concepts in 3-dimensional images of head shapes. And also it presented the methodology to pattern-making of 6-piece crown hat based on 3D data. It used the data of Size Korea to pick up and choose a head shape model with the average head size of Korean women in their twenties. Main results were: 1. The 3D scan data of head shape was better than the 1 dimensional measurement data. Because I could establish a hat pattern-making theory by the 3D scan data of head. 2. The 3D scan data provided the basis for conceptualization of basic measurement points and items for a better fit of hats as well as the definition of the basic hat circumference. 3. This presented a methodology for analyzing out head shape by 3D scan data, and allowed the derivation of the basic hat circumference from the maximum head circumference. 4. As the 6-piece Crown cloche hat made by this method fitted the head shape model perfectly, this methodology could suggest potential applicability to various hat design.