Abstract: With the exploration of oil and gas keeping into deep sea, Steel Catenary Risers (SCRs) become the preferred risers for the resource export. The dynamic model of SCRs is further discussed and a new model, named a rigid rotation model, is proposed. The model is based on the consideration of the large curvature of SCRs' static configurations and takes risers as rigid rotation systems about the axis from the hanging point to the touch down point (TDP). The rigid motion is then coupled with the bending vibration as an inertial force and hydrodynamic damping, and the out-of-plane motion with the bending vibration and the rigid motion are simulated. The case studies show that the rigid motion of SCRs affects their dynamic response greatly and can not be ignored in their dynamic analysis.