The fast pyrolysis of sawdust biomass in the tilted-slide reactor was simulated and the product yields were compared with the experimental results. The biomass was pyrolyzed during it was transferred down to the reactor with the hot sand. The steady-state simulation was performed by a commercial computational fluid dynamics code for predicting the flow, temperature, and concentration of gaseous species together with the particle behaviors. Lagrangian multiphase model was used to simulate the transport of sand and biomass particles, and the kinetic mechanism of biomass pyrolysis was adopted. It was found that the volatile yield continuously increased with temperature due to the absence of the secondary cracking reactions while there is the maximum yield in the experiment. The 1-D calculation considering the secondary gas-phase reactions of the pyrolysis products showed the maximum volatile yield at the temperature about 30 similar to 80 degrees C higher than the experimental results. At lower temperatures, the volatile yield was much smaller than the benchmark case while the char yield was much larger due to an incomplete conversion of biomass. The fast pyrolysis process in the tilted-slide reactor was investigated along the pyrolyzing particle tracks, and the solid-phase intermediate species were found to be important to evaluate the decomposition of biomass components.