The effective extraction radius of boreholes is an important index for the design of gas extraction parameters. In order to study the impact of the basic physical factors of coal (moisture content, permeability, gas pressure) on the effective extraction radius, based on the dual-pore structure of coal, consider the weakening effect of water on crack openness and matrix gas adsorption performance, both the permeability model and solid-gas multi-field coupling model that considering the impact of moisture are established; and then the multi-physics numerical simulation method and response surface analysis method are applied to analyze the interaction of the three factors on the effective extraction radius of borehole. Researches show that the effective extraction radius is positively correlated with the initial permeability, and it is negatively correlated with the initial gas pressure and moisture content. Subsequently, a response surface model on the relationship between gas drainage radius and three factors was established, and then it was found that the effects of water content, initial gas pressure, and permeability on the effective extraction radius decreased significantly in sequence. And the increase of the initial gas pressure of the coal body will weaken the influence of the initial permeability and moisture content on the effective extraction radius, and the initial permeability and moisture content will also significantly change the influence of the initial gas pressure on the effective extraction radius; however the initial permeability of the coal body hardly changes the influence of moisture content on the effective extraction radius.