The numerical simulation and model tests are used to study the motion characteristics of the coupling system of Lanjiang crane vessel and suspended object in head sea. The sensitivity of the motion of the suspended object to the change of period and wave height is analyzed. According to the Noble Denton guidelines, the capability of Lanjiang crane vessel for lifting 1 000 t and 3 000 t topsides is analyzed in East China Sea, which provides theoretical basis for the applicability of Lanjiang crane vessel in offshore operation.