Abstract: In order to solve the problem of gas control in layering mining of extra thickness coal seam in Baijigou Coal Mine,reduce the loss of coal resources,and decrease the amount of roadway excavation,a technology of retaining roadway along goaf with flexible formwork concrete was developed. The bottom layered return air laneway was used as the gas drainage roadway. The supporting form and parameters of the roadway were determined,and the double wall roadway retaining test in the field was carried out. The surrounding rock movement law of retaining roadway along the goaf in the layered mining of extra thick coal seam in Baijigou Coal Mine was obtaiend. The results show that,① The procedure of the overlying strata from collapse to the stability is completed at 60-200 m behind the layed mining working face;② The roadway deformation of the extra thickness coal seam can be divided into four stages,the mining pressure of gas drainage roadway basically presents a dynamic change of "pressurized—peak—stabilized pressure". Three multiple mining support schemes were proposed,which ensured the gas drainage roadway remained stable when the layered mining of the next section working face 1 finished. The result suggests that it is feasible to keep the bottom layered return air laneway as gas drainage roadway by adopting the flexible formwork concrete double-wall roadway retaining technology and surrounding rock control scheme.