In order to reveal the influence law of marine environment on full-circle slewing floating crane ship in marine hoisting assembly operation, a numerical model of motion response of 3 600 t full-circle slewing floating crane ship in marine hoisting assembly operation is established according to the ship motion calculation theory. The motion response of the ship in marine hoisting assembly operation is studied with the AQWA integrated module of Ansys software, including the Response Amplitude Operator (RAO) amplitudes of different sea direction angles and the motion amplitudes of different boom slewing angles. The motion response of the ship in marine hoisting assembly operation of different hoisting assembly structures is studied, including the parameters of hoisting assembly structures, RAO amplitudes of different hoisting assembly structures, and motion amplitudes of different hoisting assembly structures. The research conducted can provide certain reference for the full-circle slewing floating crane ship in safe and stable marine hoisting assembly operation.