Abstract: The coal bed gas ground well extraction test of mining subsidence area in 4308 working face of Chengzhuang coal mine in Jincheng city was done.Aiming at the geological characteristics of the test point,the body structure of test well was designed,and the drilling extraction datum before and after working face passed through were analyzed.The casing deformation were investigated four times.The test found that the extration pure flow of ground well reached to 8 m³/min.But,how to maintain the stability of casing is still a problem which should be resolved.