Dye sublimation heat transfer printing technology was developed for use in textile printing for many years. Although digitally printed textile technology grabs a lot of attentions recently, this simple, flexible process offers many advantages, such as quietness, low price, ease of color reproduction, reduced post processing, and low maintenance requirement. The textile thermal transfer printing method has been expanding into an increasing number of applications with its dry process and quick output digital image data. Color reproduction capability of a heat thermal print is highly related to the amount of dye transferred. To achieve high dye transfer efficiency and obtain best color reproduction capability, three primary parameters- the heat transfer temperature, the dwell time in the heat zone, and the pressure, need to be taken into account. The main purposes of this experimental study are to (1) identify the most important factors that influence color reproduction of polyester fabrics using heat transfer printing, and (2) establish optimum process operating conditions so that the maximum yield of color gamut and optical density could be obtained. The experiment was conducted using a randomized 23 factorial design in which every factor is run at two specified levels (1 = high level, -1 = low level). The factorial levels were determined based upon the practical operating conditions of the heat transfer press. The three independent factors of this study are: 1) the dwell time in the heat zone (X1), 2) transfer temperature (X2), and 3) the pressure (X3). The dependent variable (Y) is the color reproduction capability (optical density and gamut volume) of polyester fabrics. It was found that heat transfer temperature (X2) and dwell time (X1) are the two dominant key factors affecting color reproduction on polyester fabrics; the treatment combination of (X1, X2, X3) = (1, 1, 1) is suggested to achieve the maximum yield of optical density and color gamut.