In order to solve the problem of high content of hydrophilic oxygen-containing functional groups on the slime surface, improve the hydrophobicity of the slime surface and the floatability of the slime, a collector diesel and FO compounding agent to perform a coal sample was used in the hydrophobic modification treatment, the contact angle, induction time, and slime flotation test were used to investigate the change of the hydrophilicity of the slime surface after the chemical modification. The results showed that after the coal sample was treated with diesel fuel and FO compound agent, the contact angle became smaller, the induction time became shorter, and the effect of FO compound agent was stronger than that of diesel oil. At the same time, the use of a small amount of FO agent could achieve a higher yield of clean coal than diesel, and the ash content of clean coal also tended to decrease.