Abstract: Taking the high-ash refractory coal slurry in Kailuan area as the research object, the Box-Behnken response surface method is used to optimize the sludge flotation process parameters.The main factors affecting the amount of collector, the amount of foaming agent and the fineness of grinding are selected.The design data is analyzed by Design Expert 8.0 software, and the quadratic regression equation is obtained by fitting.The results show that the foaming agent dosage is the main factor affecting the ash content of clean coal.The optimal flotation conditions optimized by response surface methodology are grinding fineness -0.075 mm 80.76%, collector dosage 200 g/t, foaming agent dosage 231.76 g/t, under this condition, the flotation yield is 87.13%, and the clean coal ash is 12.44%.The flotation experiment results are basically consistent with the predicted values, indicating that the model is accurate and the optimization scheme is credible.