Finite element modeling was performed to study the pyrolysis of centimeter-sized biomass particles. The model proved to be accurate in predicting the intraparticle heat transfer during the pyrolysis of biomass particles at different operating conditions and for various particle properties. It was further applied to find the dominant factors of biomass physical properties influencing biomass pyrolysis, especially when the product distribution was considered. Simulation results indicate that biomass density and initial moisture content mainly affect the conversion time while have a limited effect on product distribution. With larger particle size the conversion time increases significantly. Higher tar yield with lower yields of char and non-condensable gases were predicted at smaller particle size, indicating that the product distribution can be adjusted partially based on appropriate selection of particle size.