Abstract: The powder fuel feeding system directly affects the operating stability, safety and thrust performance of the powder-fueled ramjets. Therefore, a reverse-displacement pneumatic piston powder feeding device was proposed. The effects of aluminum powder particle size and morphology on the steady-state feeding process were analyzed via a coupled Fluent-EDEM simulation.The results show that a stable packed layer is formed at the bottom of the powder hopper during feeding, with a conical particle pile accumulating beneath the feeding pipe. The airflow drives the aluminum powder to converge toward the center for continuous conveying, forming a dynamically stable powder particle distribution. Decreasing particle size markedly improves feeding efficiency. When the particle size is reduced from 150 μm to 50 μm, the efficiency rises by around 47.8%. Aluminum powders with aspect ratios ranging from 1∶1.5 to 1∶2.5 promote the rapid formation of a stable flow regime. However, the steady-state mass flow rate is decreased by about 15% when the aspect ratio reaches 1∶2.5. In summary, it is recommended that aluminum powder with a particle size of 50 μm to150 μm and an aspect ratio less than 1∶2 should be used in this feeding device.