It is important to utilize coal bed methane to achieve the safe, environmental and economic benefits. The authors simulate the processes of multijet diffusion combustion of low concentration coal bed methane using kε turbulence model，nonpremixed combustion model and P1 radiation model. The influences of different geometrical structures and operating parameters on the combustion process are compared with each other. The results show that the distance between the gas nozzles and central axis，the angle of gas deflected from air ，the velocity ratio of air to gas have important impacts on the combustion. When the distance, the deflection angle and the velocity ratio are 30 mm，45 °and 2, respectively. The best combustion result can be achieved.