SPH (smooth particle hydrodynamics) and MoorDyn numerical model were used to investigate systematically the dynamic behavior of moored floating bodies on stepped seabed. Based on the comparison with the experimental data, the influence of wave height and step height on the motion response and mooring force of moored box floating body on stepped seabed was discussed in detail. The results show that the motion response of the two floating bodies increases with the increase of wave height. The mooring power of the other three cables also show an increasing trend except for L3. As the height of the ladder continues to rise, the two floating bodies above and below the seabed ladder appear different change rules. In addition, it is found that the relationship between L2 mooring and L0 and L1 is about 3 times, and the relationship between L2 mooring and L3 is about 2 times.