The friction and wear of B4C ceramics with different contents of Al2O3/Y2O3 sintering additives were studied under dry sliding. With the increase of Al2O3/Y2O3 content, the friction coefficient of B4C ceramics decreases first and then increases, and the wear rate of B4C ceramics decreases gradually. The friction coefficient of B4C ceramics is related to the amount of wear debris generated on the sliding interface, which is determined by the competition between the number of pores that can trap the wear debris and the degree of grain pullout and grain fracture. When the content of Al2O3/Y2O3 is 5 wt%, the amount of wear debris on the sliding interface is the least, leading to the lowest friction coefficient. The wear rates of B4C ceramics are controlled by the competition of the beneficial effect of improved relative density and mechanical properties and the adverse effect of weak bonding between B4C grains due to the formation of intergranular phase. The gradually decreased wear rate of B4C ceramics with the increased content of Al2O3/Y2O3 is attributed to the improved relative density and mechanical properties.