Aiming at the safety problem of the submarine cable after being impacted by dropped objects, the dynamic process of dropped objects impacting the submarine photoelectric composite cable is simulated based on the Coupled Eulerian-Lagrangian (CEL) method. The comparative damage analysis of the armor layer and cable core on the rigid seabed and non-rigid seabed is carried out and the damage effects of different sizes, impact speeds, masses and impact angles of the dropped object are analyzed. The results show that: the damage to the submarine photoelectric composite cables on the rigid seabed is significantly higher than that on the non-rigid seabed; the armor layer is the main load-bearing component of the submarine photoelectric composite cable, the damage and deformation of the cable core could be inferred from the damage and deformation of the armor layer; with the speed or mass of the dropped object increasing, the damage degree of the submarine photoelectric composite cable increases; for cube objects, when the impact angle is less than 60°, the damage degree of the submarine photoelectric composite cable increases with the increase of the impact angle.