In order to reduce the risk of offshore installation of large offshore converter station, OrcaFlex software is used to carry out the coupled hydrodynamic analysis of the transportation and the key stages of floatover installation of Sanxia Rudong offshore converter station. Through the real ship monitoring system, the inclination angle and acceleration of the converter station during transportation and the sea environmental conditions and the movement of the barge and converter station during the floatover installation are monitored in an all-round and whole process. The measured results are compared with the numerical simulation results, and the two are well compared, which further verifies the reliability of the numerical calculation.