Abstract: The output of coal fines is one of the key issues affecting the efficient development of CBM. The blockage of coal fines will cause the pump to be buried and stuck in the CBM well, increase the number of workover operations in the drainage and production of the CBM well, and affect the efficient development of the CBM well. Since the content of inorganic minerals in the coal fines produced by the coalbed methane wells is as high as 50%, in order to find out the effect of different dispersant types on the dispersion of mudstone particle suspensions with different particle sizes, the Taiyuan Formation of the Hancheng block in the eastern margin of the Ordos Basin was selected. 11# coal seam roof mudstone sample, carried out the dispersant optimization experiment of mudstone particles with different particle sizes, analyzed the static stability and mass concentration characteristics of mudstone particle suspensions with different dispersants, and discussed the effect of dispersants on mudstone particles with different particle sizes and different dispersants. Effects on the dispersion stability of mudstone particles of the same size. Optimizing dispersants with relatively good dispersing effect applied to CBM well-washing technology. The experimental results show that different dispersants have different effects on the dispersion stability of mudstone particles with different particle sizes. With the increase of particle size, the dispersion stability of mudstone particle suspension of SDS and SDBS dispersants becomes worse; the dispersion stability of mudstone particle suspension of SN dispersant does not change significantly. With the increase of standing time, the dispersion stability of mudstone particle suspensions with different dispersants decreases, and the mass concentrations of mudstone particle suspensions with different dispersants all decrease to varying degrees. The mudstone particle suspension of SDS dispersant has the largest mass concentration of mudstone particles under the conditions of different particle sizes and different standing times. The straight-chain alkane hydrophobic base of SDS is more easily adsorbed on the surface of mudstone particles, which can play a good dispersion effect on mudstone particles of three sizes, and has strong suspension dispersion effect and static stability. Based on the differences in the dispersion and suspension stability of coal fines and mudstone particles with different types of dispersants, it is suggested that SDS should be selected as the dispersant in the CBM well-washing technology.