Abstract: Alternating spout deflection is a common instability problem in spout-fluidized beds. Geometrical modification to the reactor is a feasible way to mitigate the deflection. In this work, three kinds of geometrical designs are studied to mitigate the alternating spout deflection by the CFD-DEM approach. Design I is to add baffles at the top of two annulus regions. The results demonstrate that this design can significantly reduce the amplitude of spout deflection by reducing the stamping of falling particle flow on the annulus regions. Design II is to install two zigzag-like baffles in the fountain region, which is expected to disperse the particle distribution in the fountain region. However, this solution leads to non-alternating spout deflection, which is undesirable in the application. Design III is to modify the slot angle of the reactor bottom. The results show that 30° slot angle increases the frequency of the alternating spout deflection but rarely affects its amplitude. Non-alternating spout deflection occurs with 45° slot angle. This work benefits the hydrodynamics stability in spout fluidized beds.