The invention relates to a method for producing disperse blue dye, which is characterized in that: C.I. disperse blue 56 original dye is added into a reaction vessel, dissolved by a proper quantity of DMF, a proper amount of magnesium oxide is added to be used as an acid binding agent, a proper amount of benzoyl chloride is added drop by drop into the reaction vessel under the condition of stirring, heated, after adding is finished, then reacted by isothermally stirring to obtain a reaction product; the reaction product is diluted into a proper amount of icy water, the temperature is maintained less than 15 DEG C, filtered, water is added to filter cake for pulping, the temperature is raised until 55 DEG C to 65 DEG C, the temperature is kept for 2 to 4 hours, then processes of standing overnight, filtering and then washing, drying are performed to obtain disperse blue dye. According to the invention, disperse blue dye solves a technical problem of disperse dyes in transferring printing, the washing fastness, friction fastness and light fastness and the like of the transfer products are obviously improved, disperse blue dye has less sewage and a high utilization rate during the use. The invention provides a rare and novel disperse dye used for transferring printing.