When navigating in coastal areas, a ship may collide with a coastal bank, resulting in grounding. This issue involves interactions among the wave, the ship, and the coastal bank, with the key aspect being the contact between the ship and the bank. To solve this problem, a smoothed particle hydrodynamics (SPH) method is employed to simulate wave motion, wave-ship interaction, and wave-bank interaction. A discrete element method (DEM) is used to handle the interaction between the ship and the bank. Accordingly, a coupled SPH-DEM approach is established to study ship grounding. Numerical analysis is conducted for a bank with a 1:10 gentle slope under three wave periods, focusing on ship motion responses of pitch, surge, heave, and contact forces between the ship and the bank. The results show that under short-wave-period conditions, the ship remains grounded on the bank with small motion responses. Under the long-wave-period condition, the ship lifts off the bank and floats freely, with significantly increased motion responses. Regarding the contact forces between the ship and the bank, the vertical components are significantly larger than the horizontal components. In the early stage of grounding, the vertical components of the contact forces reach their peak values, accounting for up to 65.52% of the ship's gravity for all test cases. In the stable stage, the vertical components account for 32.84% and 41.89% of the ship's gravity for the two short-wave-period cases, and decrease to 0% for the long-wave-period case as the vessel is no longer grounded.