Abstract: In the process of cementing in caolbed methane （ＣＢＭ） wells, due to the low pressure of gas well, the common cementing mud is easy to leak out and infiltrate into the coal reservoir, which blocks the gas-producing pores and passageways of the reservoir, reduces the gas-producing capacity of the coal seam and affects the cementing quality. To solve this problem, we need to study a kind of cement slurry system to balance the formation pressure, and the slurry needs rapid solidification at the same time and the early strength rises faster to form a closed stable channel in a short time and further reduce the influence on coalbed methane gas and achieve the goal of effective cementing. At the same time, the oil well cement cost is high, difficult to obtain. Therefore, it is of great significance to study low cost and high efficiency cementing slurry. Three kinds of relatively easy materials, namely glass beads, ordinary Portland cement of model PC42.5R and sulphoaluminate cement of model R.SAC42.5, were used to combine in different proportions, speeding up its setting time, through testing the curing strength of the pumping stage, initial setting time, final setting time and 24 h, 48 h, 72 h, the formula of modified low density composite cement was preliminarily explored according to the actual requirement of high efficiency cementing of coalbed methane well.