The invention provides a synthetic process of low-chromaticity polyester polyester polyol. The synthetic process comprises the following steps: (A) using polyol and polyacid or poly-anhydride as raw materials, performing the esterification reaction at 140 to 215 DEG C, and dehydrating; (B) until the acidic value of the reaction system being 20mgKOH/g or below, adding a catalyst, adjusting the temperature to be 215 to 230 DEG C, performing the esterification reaction, and dehydrating; and (C) until the acidic value of the reaction system is lowered to 2mgKOH/g or below and the pressure of the reaction system is lowered from the normal pressure to be 0.01MPa or below, vacuum dehydrating, and obtaining the low-chromaticity polyester polyol, wherein the chromaticity of low-chromaticity polyester polyol is APHA10 or below. By adjusting the temperature at each phase in the preparation process of the polyester polyol preparation process and by adjusting the synthetic process, the synthetic temperature, the program control, the catalyst as well as the matching of the consumption and temperature programs and the like, the chromaticity of prepared polyester polyol is very low.