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Binder jetting (BJT) has been extensively explored for additive manufacturing of ceramics due to its ability to create complex structures by processing refractory and hard-to-machine materials. However, achieving a uniform powder bed with high packing density while processing ceramics in BJT remains a challenge. This study systematically examines the role of powder size, powder temperature, flow behavior, and powder size distribution on powder bed formation and resulting part properties. Four different alumina powder sizes (1 μm, 5 μm, 10 μm, and 20 μm) were investigated. Flowability characterizations reveal that 1 μm powder remains poorly flowable at both room and elevated temperatures, while 20 μm powder demonstrates excellent flowability at both temperatures. Smaller powders, especially 1 μm, exhibit around 25% loss in moisture, which results in pronounced agglomeration at room temperature. Discrete element method simulations were used to identify the ideal mixing ratio of the bimodal powder using 5 μm and 20 μm powders. For bimodal powder, both the simulation and the experiments exhibited a preferential deposition of smaller powders in the spreading direction. However, the 5 μm and 20 μm powders did not show any preferential deposition in the simulation, but experiments showed preferential deposition behavior. When using bimodal powder, packing density decreases by 7.65% along the spreading direction, which aligns with an 8.19% drop in part relative density. These findings offer valuable insights into the effects of bimodal powder distribution for controlling powder bed packing density and potentially leveraging spatial density variations for functional applications such as biomedical implants, heat exchangers, and gas filtration.