Abstract: To exploration the effect of the desulfurization and ash reduction by flotation reagents of diethyl phthalate,take the middle and high ash content,middle sulfur Taiyuan coal,and middle and high ash content,high sulfur Luan as research object,through orthogonal test to determine the best pulp density and the best dosage of reagents,on this basis carried out the flotation compared tests of the diethyl phthalate and kerosene.The study results showed that,the effect of the desulfurization and ash reduction for middle and high ash content,middle sulfur Taiyuan coal slime with diethyl phthalate is better than with kerosene.For flotation Luan coal slime,the best dosage of reagents of the diethyl phthalate is 1.00 kg/t,the clean coal yield and flotation perfect index is higher by 17.55% and 16.69% respectively than those of the kerosene,the clean coal sulfur content and ash content are lower by 0.78% and 3.39% by use of kerosene respectively.