The study of swirling jet combustor for biomass coal co-firing is of great interest for energy industry. The biomass co-firing can serve as a NO_x reduction method as well as the better use of renewable energy source. Large eddy simulation (LES) and RANS modelling have been performed with two different burner designs. Usually pulverized coal-biomass mixture enters the furnace along with primary air through primary pipe, and the secondary pipe provides necessary air and mixing for combustion. The improved model has three passages including primary, secondary and middle passage for swirling. The simulations on two geometries have been compared, and the aim is to design a better and improved burner model for better pre-combustion mixing in the biomass co- fired furnace. The results from two-way and three-way geometry have been compared with each other as well as with the results from the furnace model used by Apte and Mahesh [8].