The invention relates to a synthetic method of dye intermediate esterifying fluid. The synthetic method comprises the following steps of adding dehydrated hydroxide and acetic acid to an esterifying kettle, wherein the dehydrated hydroxide and the acetic acid are fed according to the mole ratio of hydroxyethyl contained in the hydroxide to acetic acid being (1 to 1) to (1 to 10); raising the temperature under a stirring state, and after the temperature rises to 110-150 DEG C, promoting an esterification reaction to perform through rectification and dehydration; at the later stage of the esterification reaction, adding molecular sieves of which the channel pore diameter is smaller than 9A to the esterifying kettle, wherein the addition mass of the molecular sieve is 1-25% of that of the dehydrated hydroxide, and continuing the reaction until the reaction is finished under the condition that 110-140 DEG C reflowing state is maintained; after the esterification reaction is finished, enabling products to be separated from the molecular sieves so as to obtain high-purity esterifying fluid; and performing regeneration and activation treatment on the separated molecular sieves, so that the regenerated and activated molecular sieves can be recycled. The reaction condition of the synthetic method disclosed by the invention is relatively mild and easy to control, the reaction rate, the quality of the products and the yield of the products are notably increased, the cyclic utilization of resources is realized, and the cost is effectively reduced.