Abstarct: Combustion is a complicated process which needs the simultaneous solutions of continuity equatin, Navier-Stocks equations and energy equation for its analysis. In the two recent decades the Lattice-Bolzmann method has been identified as an appropriate substitute for complex numerical analysises. Utilizing the lean premixed flames in the burners , compared to non-premixed flames, not only does decrease the energy consumption but also produces less pollutant gases due to the lower temperature of combustion products. However, it has some obstacles on the way to be practically applied in spite of its great advantages. The released heat in the combustion process is low for lean premixed flames, hence; the generated flame encounters instability and consequently is extinguished. In the present study, the stability of the flame in the lean premixed flame in a stratified burner has been investigated baxsed on the location of air and fuel injection in each laxyer of the burner. Presence of a Bluff-body at the flame exit is considered as an effective factor in improving the stability of the flame. Selected boundary condition of constant pressure at the outlet of the burner, the flow solution with some errors. In the current study, propane is the fuel used for the experiments. Impacts of parameters of velocity equivalence ratio and effect of air inner/outer injection have been investigated on the midean flame. In the intial mode, air and fuel enter the burner in a premixed way through the median laxyer, and it is observed that by increasing the equivalence ratio at a constant speed, the flame reshapes and starts reaching the stability. At the speed of 1 m/s, the tip of Lift-off flame bends toward the upstream of the flow, and by devating of this speed the root of the Llift-off flame rises. In the second mode, by outer injection of the air into the flame with a relatively high flow speed in comparison to the initial mode, the reshape and stability of the flame are observed which are attributed to the fact that the injected air plays the insulater role against the ambient cold flow and prevents the flame from being extinguished. In the second mode, by inner injection the air into the burner, there have been observed no meaningful impacts in comparison to the two other modes.