Considering the characteristics of a 6×19 multi-strand mooring cable, the stress response of the cable under the combined action of tension-torsion-bending is investigated. The helix equation of the multi-strand mooring cable and the axial distance between the contact points of different layers of strands are derived, the representative volume element (RVE) in the simulation model is established, the periodic boundary conditions (PBC) under the RVE are derived, the simulation model of the multi-strand mooring cable is simplified, the strain and curvature loading methods are further optimized, and the loading form of the simulation model is optimized. The simulation analysis is carried out in the finite element software ANSYS and compared with the theoretical model at the same time. The results show that RVE and PBC selected are reliable, the stress is non-linearly negatively correlated with the radius of curvature, the strain is linearly positively correlated with the stress, and the interaction between radius of curvature and strain is mainly in the value and location of the maximum stress, which is of less influence on the stress-strain relationship.