Si3N4 ceramics composite with different contents of hBN were prepared by hot pressing, and the tribological properties of Si3N4-hBN ceramics composite and Ti6 Al4 Vtitanium alloy in seawater environment was studied by MMW-1 vertical universal friction and wear tester. The wear morphology of the material was observed by scanning electron microscope（SEM）, and the elemental distribution of the friction surface was qualitatively analyzed by EDS spectrometer and the elemental distribution of the friction surface film was qualitatively analyzed. The result shows that the addition of hBN reduces the physical and mechanical properties of Si3N4 ceramics;under the conditions of seawater and 20 Nand 1 000 r/min, the friction coefficient and wear rate of pure silicon nitride（0. 467, 1. 01×10-5 mm3/Nm）are higher than that of hBN content 5%（0. 411, 5. 58×10-6 mm3/Nm）and 10%（0. 417, 6. 55×10-6 mm3/Nm）and lower than hBN Si3N4 composite ceramics with 20%（0. 505, 2. 07×10-5 mm3/Nm）and 30%（0. 485, 1. 34×10-5 mm3/Nm）content. Therefore, under the seawater environment, when the hBN content is 5%, the friction coefficient and the wear rate of the pair are the lowest, indicating that SN5 has good tribological properties, which is attributed to the formation of SiO2、TiO2、Fe2O3、Al（OH）3 and Mg（OH）2 materials with lubricating action on the surface of the TC4 disc. These materials can not only improve the friction coefficient of the sliding pairs, but also protect the worn surface. [ABSTRACT FROM AUTHOR]