Tribological behaviors of Si₃N₄ based ceramics against POM were investigated in distilled water and seawater as well as dry sliding condition, respectively. It was found that the effect of sliding speed on the tribological properties of system is greater than that of the load. During the drying-sliding condition, as the sliding speed raises, the amount of frictional heat is continuously output, resulting in the melting of POM. The melted polymer is transferred to the surface of ceramic to form a layer of transfer film, and the main wear is the adhesion-peeling off between the sliding surfaces. In aqueous solutions, abrasive wear is the main wear mechanism. Furthermore, due to the lubricity effect of seawater and tribochemical degradation of POM, the wear degree of Si₃N₄ is effectively reduced.