Abstract Based on Kaimal spectrum, a stochastic simulation for along-wind velocity time history is generated with the numerical method of a multidimensional homogeneous process. Applying the acquired stochastic wind load to the FEM model of the 7500t floating crane’s boom, time-domain dynamic analyses are respectively implemented in the conditions of the clearance considered or ignored, which shows that the axial clearance between boom root and pin hinge will intensify the wind-induced lateral vibration of the boom in the horizontal plane, and also illustrates that dynamic wind load is the primary cause of the vibration. Hence, a new method of filling the clearance with rubber spring is proposed in order to reduce lateral vibration. By studying the influence of altering rubber spring’s length and hardness on natural frequency, the maximal displacement, as well as the peak reaction force value to the boom, the optimal parameters of rubber spring are obtained. When the length of rubber spring is about 200mm to 400mm and Shore hardness is about 30 to 50, the optimal effect of vibration reduction is achieved: the maximal displacement decreases by more than 13%, comparing with that in the condition of the clearance considered. It shows that the proposed method of filling the clearance between boom root and pin hinge with rubber spring is feasible for lateral vibration reduction.