The dyeing of polyester with disperse dyes has been practiced for the last 60 years. Nevertheless, the dyeing recipe is typically decided by experience based on dye house experts' judgment. This study aims to provide a fundamental understanding of the overall polyester dyeing process, from dye uptake by fibre in a microscopic view, via analysis on the coloration of dyed product, to the operational optimization in the actual process. Through such an understanding, a better process for obtaining a product of the desired quality can be developed. For this, bench scale dyeing experiments were carried out in a special-designed dyeing tank and dye uptake by the fibre were monitored by real time dye solution sampling. Arrhenius and William-Landel-Ferry equations were applied for the changes in dye uptake rate by polyester. Relationship between the three-phase structure for polyester and the dye uptake ability was also studied. Plasticizing effect of one common carrier and solubilizing effect of surfactants were investigated individually. These effects were then related to the color evenness and the luminance of the final product based on the analysis on the final coloration in the CIE L*a*b* Colorspace. Tests on cotton and reactive dyes were also carried out, showing the capability of the experimental setup for various situations. With the understanding on the impact of various effects on the quality of the dyed product, three schemes for process optimization on reducing process time, energy and amount of additives have been proposed and tested.