During the voyage, the ship will be subjected to complex alternating loads under the influence of seawater. The purpose of this paper is to study the effect of alternating load on the static and dynamic performance of tilting-pad journal bearing (TPJB). Under the given alternating load, the static and dynamic performances of bearing in ideal condition and misalignment state are obtained by numerical methods. The results show that the pressure, temperature, and stiffness of the bearing are greatly affected by the alternating load. Meanwhile, as the degree of misalignment increases, the fluctuation of oil film temperature and oil film stiffness under alternating load is obvious. In this case, bearing instability is easy to occur. This study can provide a reference for the design and reliability analysis of sliding bearings for marine use.