Abstract: Taking CBM wells in a block of Qinshui Basin as an example, through analyzing the typical drainage and mining index of CBM well, this paper studies the influence of fracturing scale on drainage and mining index, and probes into the mechanism of the influence of different fracturing scales on the typical drainage index. The results show that: the water and gas producing of CBM wells after fracturing mainly depends on the energy and channel conditions of coal reservoir; the fracturing scale of CBM wells in the study area is between 80 m³/m to 200 m³/m, accounting for 86% of the total wells; the cumulative water production index, the cumulative water production before casing pressure and the rate of backflow have nothing to do with the fracturing scale index, but the cumulative gas production and the average gas production have something to do with the fracturing scale index; with the increase of fracturing scale index, the cumulative gas production and average gas production increase. When the fracturing scale index exceeds 140 m3/m, the cumulative gas production and average gas production decrease as a whole.