Abstract: With the gradual depletion of high-quality anthracite resources,the low-rank coals with abundant reserve are proposed to produce ultra-clean coal by scholars at home and abroad. However, when using conventional flotation agents to float ultra-fine particles,the agent consumption is high and the separation is poor. In order to improve the flotation effect of ultrafine particles of low-rank coal,the Shendong long-flame coal with ultrafine particle was investiga- ted in this study. The nonionic surfactants (Triton X-100,Span-80) and conventional collector (kerosene) were used as raw materials for the preparation of new compound flotation agent. The regression models between the ratios of compounding agents and ash and yield of flotation concentrate were established by D-optimal mixing design test. The effect of different ratios of Triton X-100,Span-80 and kerosene on the ash and yield of flotation concentrate were studied and the effect and interaction of factors in compounding agents were discussed by factor analysis and response analysis. By optimizing the test,the optimal ratio of the compounding agent was obtained. The results show that the ash content and yield of flotation concentrate are not only affected by the single factor of the compounding agents of Triton X-100 (A), Span-80 (B) and kerosene (C),but also by the interaction between the compounding agents. When the proportion of B or C is high,it will have a significant impact on the ash content and yield of flotation concentrate. The effect of the compounding agent on the ash content and yield of flotation concentrate are:B>C>A. There are significant interactions between A and B,B and C,the specific effect of the interaction between the compounding agents on the ash content and yield of flotation concentrate are:BC>AB>AC. The best formula for the compound collector was determined to be as follows:0. 7% of Triton X-100,1% of Span-80 and 98. 3% of kerosene. The ultra-clean coal with 1. 54% of ash content and 56. 04% of yield can be obtained in the flotation experiments under the optimal formulation conditions. Compared with the conventional collectors under the same test conditions,the compound collector which had a better flotation effect had the advantages of reducing the agent consumption,improving the yield and reducing the ash of flo- tation concentrate.