The objective of this research was to study the optical illusion effect and the difference of image of textile pattern design. This research also tried to show the more useful method to make stimulus by computer simulation and to present quantitative data. For the experiment, 3 design variable were selected from design principal book as follows : size, arrangement and value harmony of motive. Size of motive variable was divided into 3 level so by use of check & dot pattern, arrangement of motive variable was manipulated to vias direction for check pattern and value harmony between motive & base color was classified into similar value harmony and contrasting value harmony. Visual stimuli which same model was wearing each design were created by ENVISION program. This photographs were given to evaluating panels, Then panels compared experiment design by slim effect and evaluated for 5-sementic differential scale expressing clothing image. The results were as follows : 1) There were significant difference is slim effect, clothing image as simplicity and boldness according to size of Motive. 2) Arrangement of motive for check pattern had significant effects on slim , clothing images as activity and attractiveness. 3) Case of low value base color and high value dot color has significant high score on slim effect, activity, attractiveness, boldness and youthful image.