For a new type of multi-segment pontoon bridge with alternately supported floats in the span range, a theoretical model of the dynamic response that can simultaneously consider the roles of connection hinge stiffness and float support stiffness is established.In the model, the pontoon segments are regarded as Euler-Bernoulli beams with hinges at both ends, and the action of the floating body and the hydrostatic water is equivalent to the elastic support distributed along the length of the beams, and the neighbouring segments are connected by hinges with rotational stiffness.The relationship between the structural self-resonance characteristics and the moving vehicle load response with the above two stiffness parameters is investigated.The results show that: the method can obtain the response sensitivity interval of the floating body support stiffness and the rotational stiffness of the connection hinges; with the increase of the rotational stiffness, the segment connection transitions from articulation to rigidity, and the relative angle of the two ends of the hinged joint in the modal state is changed from the “sharp angle” mutation form to the smooth form; when the rotational stiffness is smaller, there is the vertical direction of the connection.When the rotational stiffness is small, there are vertical displacement extremes and corner mutations in the connection, and the structural displacement and internal force envelope tends to be stable after increasing to a specific value.