Abstract: The effective pressure drop radius of coal reservoir should be enlarged as far as possible to improve the gas production of CBM well. By analyzing the complementary variation law of water production and gas production during the process of CBM well drainage, the multiple coal seam development well group in Guizhou area and the single coal seam development block in Shanxi area are taken as examples to analyze the influence of water production on gas production, and the CBM well extraction measures to increase production efficiency is proposed. The results show that: the CBM wells have changed the gas-water output ratio before and after the casing pressure, and have obvious complementary changes: the CBM wells developed in single coal seam and multiple coal seams all found that the higher the fracturing fluid flow-back rate, the higher the total gas production and average gas production; influenced by the energy and permeability of the formation, the flow-back rate of fracturing fluid in coalbed methane wells has a turning point with the change of burial depth, the transition depth is the appropriate fracture depth for the CBM well in this well area; in order to maximize the effective pressure drop radius of the CBM well, the permeability damage during the drainage process should be minimized, and the blockage of the pores of the pores by the pulverized coal particles should be reduced.