Abstract: In order to analyse the fracturing fluid damage to the Xishan coal reservoir, used the working fluid evaluate methods was used, the effect of fracturing fluid, clay stabilizer and surfactant on coal reservoir was studied. The results show that the active hydraulic fracturing fluid used in the field does harm to the coal reservoir, and the damage rate is 37.2%, the clean degree of fracturing fluid base has great influence on the degree of damage of coal seam, and the damage of theun filtered water is much bigger than that of the filtered water and well water, clay stabilizer KCl dosage should be determined according to the water-sensitive damage degree, the appropriate adding amount of clay stabilizer in the study area should be 2%~4%, in order to ensure that the fracturing fluid returns to the exhaust as soon as possible, the surface active agent should be added in the fracturing fluid, the amount, surfactant should be better at 0.2%, the actual application can be adjusted, but not more than 1.4%.In the actual production of fracturing fluid is optimized by the method, the gas production of optimized fracturing fluid CBM wells is 300~500 m³ higher than that of not optimized gas wells.