In this study, a beam-connected-discrete-modules (BCDM) hydroelastic method is employed to conduct hydroelastic analysis of large container ships with forward speed. The large container ship is discretized into several rigid modules connected by a hull girder. Considering the hydrodynamic interactions between modules, the multi-body hydrodynamic theory is adopted to obtain the hydrodynamic coefficients of each module. Subsequently, the hydroelastic equation is established by coupling the hydrodynamics of modules with the structural stiffness of the hull girder. The BCDM method replaces the boundary value problem solved in the modal space with extensively studied multi-body hydrodynamics. In particular, the derivation of generalized restoring matrices associated with flexible modes could be avoided, which has been ongoing debate for more than two decades. The effect of flexible deformation on a large container ship is investigated. To account for the influence of forward speed, the wave natural frequency is replaced by the encounter frequency. The results show that the flexible deformation increases sectional forces, especially at the structural vibration frequency.