Abstract: Biomass gasification is one of the effective thermo-chemical methods to extract energy from biomass. This study mainly focuses on 2D modelling and simulation of biomass gasification in a bubbling fluidized bed gasifier using computational fluid dynamics (CFD) solver ANSYS FLUENT 15.0. Separate phases are used for biomass (saw dust), sand and gases and all the phases are solved using Eulerian- Eulerian approach. The effect of turbulence on computational fluid dynamics modelling of fluidized bed reactors is analyzed by comparing the results obtained from laminar and turbulent cases. The developed model is used to predict the effect of equivalence ratio, steam to biomass ratio, steam temperature and air preheating on product gas composition. It is found that when equivalence ratio is increased from 0.15 to 0.4, H2 concentration is decreased by 72% and the variation of steam to biomass ratio from 0.5 to 1.5 enhanced the H2 concentration by 87%.