A novel dual pneumatic feeder was developed to achieve constant and steady biomass conveying for pyrolysis. To facilitate the feedstock replenishment, an injection pipe was installed inside a pressure chamber to convey the feedstock. Another stream of gas entered the pressure chamber from the bottom to fluidize the particles. Experiments were performed to test the performance of the new feeder, and three injection pipes and gas distributors were used. Results showed that the feeding rate depended on both the injection and fluidizing gas velocities. The feeding rate decreased with the inner diameter (ID) of an injection pipe, due to its impact on gas velocity, while the effective injection distance had a negative effect within a certain range. The opening ratio of the gas distributors had a positive effect on the feeding rate. Then, a model was developed, based on the Ergun equation, to describe relationships between the feeding rate and the gas velocities. The classical equation was further reformed to establish the correlation between the solid mass flowrate and the construction parameters of the feeder. The developed model deviated from the measured values within ± 15%, which was considered capable to predict the feeder performances.