Abstract: Under the hostile submarine conditions, the dynamic characteristics of a submarine fluid conveying pipeline in a suspended span is quiet different from those of a pipeline on land, which was affected by the coupling effect of the flows inside and outside the pipeline. An attempt is made to use the differential-quadrature method (DQM) to solve the vertical vibration of the pipeline, with the influence of both the inside and outside parameters on the vertical vibration taken into account, such as the flowrate and fluid pressure inside the pipeline, the flowrate and damping outside the pipeline and axial force. The dynamical characteristics and how the permitted suspended span varies with the flowrate inside and outside the pipeline, axial force and fluid pressure inside the pipeline were calculated and analyzed. The results indicated that DQM is successful to the analyses of dynamical characteristics of the pipeline suspended span and its fatigue and reliability design.