Abstract: High capillary pressure will be produced when the fracturing fluid containing microorganisms is pressed into coal reservoir. There is a tendency that the capillary pressure will increase as the microorganisms produce gas, which is likely to cause serious water blocking damage. In this paper, adding surfactant is adopted to control water blocking damage. The efficiency of reducing capillary pressure of coal reservoir by surfactant AN and the compatibility of surfactant AN and the fracturing fluid containing microorganisms is tested for the study of the applicability. The results show that adding surfactant AN can reduce the capillary pressure, and is beneficial to mitigate water blocking damage. On the other hand, during the gas production, surfactant AN will be consumed. Until the end of gas production, partial surfactant AN remains active which has some effects on reducing the capillary pressure, and it would not influence gas production. Therefore, adding surfactant AN to the fracturing fluid containing microorganisms is applicable.