Abstract: To address the issue of insufficient disturbance and poor mixing of biomass particles during their flow within the down-tube pyrolysis reactor, this study investigates the influence of an inclined platform inside the down-tube on the flow characteristics of ceramic balls and biomass particles. The focus of the research is on the flow behavior of biomass particles in the down-tube, where an inclined platform was designed, and its impact on particle mixing was analyzed through both experimental and simulation methods. The parameters of the inclined platform, including its position, tilt angle, and height, were treated as experimental variables, while the degree of particle dispersion was used as the evaluation criterion. The particle flow process was simulated using Computational Fluid Dynamics (CFD) coupled with Discrete Element Method (DEM) simulations. To verify the accuracy of the simulation results, Particle Image Velocimetry (PIV) technology was employed.The research findings indicate that the height of the inclined platform had the most significant effect on the dispersion degree of the particles, followed by the platform’s position and tilt angle. After multiple rounds of optimization experiments, the optimal working parameters were determined: the bottom of the inclined platform was positioned 245 mm from the corner of the down-tube, with a height of 27 mm and a tilt angle of 149°. Under these optimal conditions, the degree of particle dispersion increased by 50.24%, significantly improving the homogeneity of the particle mixture. The introduction of the inclined platform had a marked influence on the flow characteristics of the particles. Compared to the conditions without the inclined platform, the axial average velocities of the biomass particles and ceramic balls decreased by 14.38% and 11.43%, respectively. Concurrently, the average residence time of the particles increased by 20.00% for biomass particles and 5.75% for ceramic balls. These results indicate that the inclined platform effectively extends the residence time of the particles within the down-tube, thus providing more opportunities for pyrolysis reactions, which in turn enhances the efficiency of the reactor.Moreover, the introduction of the inclined platform altered the flow characteristics of the particles. In the absence of the inclined platform, the particles exhibited distinct centripetal flow characteristics, leading to uneven particle distribution with a segregation phenomenon, where particles were denser at the bottom and sparser at the top. However, with the inclined platform in place, the flow of particles became parabolic, effectively disrupting the segregation and resulting in a more uniform particle distribution. This change not only improved the homogeneity of the particle mixture but also facilitated more thorough reactions during the pyrolysis process, further enhancing the pyrolysis efficiency.The inclined platform design proposed in this study is of significant importance for optimizing biomass pyrolysis reactors. By improving the mixing effect and flow characteristics of the particles, the inclined platform not only increases the homogeneity of the particle mixture but also optimizes the pyrolysis performance of the reactor. This study offers new insights into the design and optimization of down-tube biomass pyrolysis reactors and contributes to the further development and application of biomass pyrolysis technology. It is especially valuable in enhancing biomass energy utilization efficiency and accelerating pyrolysis reactions, which have important practical implications for advancing biomass pyrolysis technology. The findings of this research hold great potential for improving the efficiency of biomass utilization in pyrolysis processes and for developing more efficient and effective biomass energy conversion technologies.