Aiming at the problem that“Tianlin”cutter suction dredger constructions under medium-long period wave abroad,we establish the wind and wave computing model of“Tianlin”,and calculate the wave force acting on the hull under different wave heights,periods and directions.We obtain the load of wire rope of three-cable positioning according to the static equilibrium method,and determine the maximum wave height that cutter-suction dredger can construction according to the maximum load.The results show that with the increase of wave period,the wave force on the “Tianlin” gradually decreases in the range of medium-long period,the force on the wire rope of three-cable positioning also gradually decreases.When the wave period is between 13 s and 16 s,the maximum righteousness wave height that the “Tianlin” can construct is 0.55 m,and the maximum righteousness wave height that “Tianlin” can construct against the wave is 0.76 m.