Numerical calculation of vortexinduced vibration (VIV) of reinforced thermoplastic pipe (RTP) based on scale adaptive simulation (SAS) and computational structure dynamics (CSD) is addressed. The VIV response of polyvinyl chloride (PVC) riser and the modal of composite plate are numerical calculated and compared with experiment data which verified the accuracy of twoway fluidsolid coupling simulation and composite modeling method. Moreover, the VIV response of RTP and the same size steel riser in different conditions are calculated. The results show that the ‘lock in’ phenomenon occurrs when the free stream velocity equals 0.1m/s. The vibration response in incoming flow direction of RTP is as important as cross flow direction. The motion of the middle section of the RTP are in disorder due to the 3dimensional effect of flow and the vibration of incoming flow direction. When the velocity is 0.2 m/s, the incoming flow and cross flow direction amplitudes of the steel riser are smaller than those of the RTP riser, and the steel riser mainly showed low order vibration. The amplitude of the RTP riser under hingehinge constraint is slightly larger than that under the fixedfixed constraint, and it mainly showed switching motion of the second or third mode.