Binder jetting additive manufacturing is a promising way to process ceramic materials which are hard to be manufactured into complex shapes using conventional methods. However, the application of binder jetting is limited by the relatively low density of manufactured parts. Powder bed forming process is a critical step that determines the powder bed density and consequently the part density. Thus, investigating and understanding the power spreading process is necessary to improve the part density. A numerical model is developed to predict the powder bed density under different spreading conditions using the discrete element method (DEM). The predicted DEM results are compared with the prediction of an analytical model. The results show that under different layer thicknesses (50 m, 70 m, 100 m) and roller diameters (12 mm, 14 mm, and 16 mm), the predicted maximum powder bed density by these two models has nearly the same value and the predicted maximum packing stress has the same trend.