Abstract: This paper establishes the computational model of hoisting operation in mooring floating cranes，based on the 3-D potential flow theory and the MOSES computing software. In particular，the movements of the hanging object and the crane are analyzed on six degrees of freedom，the swing motion of the hanging object around the boom point is investigated，and the kinetic characteristic of the ship is then presented. Also，when performing the calculation in the time domain，the model incorporates several marine parameters such as wind，waves and flow to make the result more accordant with engineering practice. To validate the proposed model，a particular floating crane is examined in experiments. The Center of Gravity（CG）of the hull and the center of the hanging object are first defined as two key points，and the tension on the mooring cable is correspondingly adjusted within a safe range. By gradually changing the hoisting condition，the movement of the hull and the hanging object can be analyzed，and the relationship between the rolling of the crane and swing of the object is revealed.