Abstract: The ultrafine disperse dye red 60 was prepared by milling method,and then investigated the effect of dispersion stability of disperse dye on synergistic effect of polystyrene maleic esterified esters (PSMA) and fatty alcohol polyoxyethylene ether(AE). The results showed that the particle size of ultrafine disperse dye was 230nm when using PSMA, whereas the particle size of disperse dye was about 174 nm, and disperse rate constant increased from -2.88 to -3.48 by using PSMA and AE formulated dispersants under the same conditions. The performance comparisons showed that using the mixture of PSMA/AE dispersant, its thermal stability increased by 6 % and centrifugal stability increased by 4 %. It was found that the dyeing speed and levelling effects of ultrafine disperse dye that prepared by PSMA/AE formulated dispersants were obviously superior to the one prepared by PSMA when dyeing polyester fabric.