Abstract: We collected the coal sample of Wulihou Coal Mine as the research object, used the surfactant fracturing fluid (1.5% KCl + 0.05% AN), by the experiment that test surface tension and contact angle, revealed the mechanism of increasing production by changing surface physical nature of the coal reservoir. The result showed that: the surfactant components in the surfactant fracturing fluid can be adsorbed physically onto the coal reservoir surface, which changed the physical nature of the coal reservoir surface. Surfactant fracturing fluid can reduce the critical pore size of coalbed methane output, promote coalbed methane desorption, and increase desorption and yield was achieved; it can reduce the pore throat capillary pressure of coal reservoir, promote the discharge of fracturing fluid, reduce the damage of water-lock on the permeability of coal reservoir effectively, increased permeability and yield by preventing water-lock was achieved; it can improve wettability of coal powder, promote coal powder settlement, reduce the damage of velocity sensitivity on permeability of coal reservoir effectively, increased permeability and yield by preventing velocity sensitivity was achieved.