Aiming at 28 inch long-distance landing submarine pipeline in the East China Sea, which has several places of suspended spans and 3 km pipeline offset accidents at 63 km offshore, the survey data of the historical buried depth change of the landing pipeline over the years are comprehensively analyzed. Combined with the regional marine hydrogeological conditions and sediment dynamic conditions, the possible causes of the accidents are analyzed through the theoretical numerical calculation of Vortex-Induced Vibration (VIV) critical span length, fatigue life and lateral stability, so as to put forward the optimal protection measures based on the risk and the comprehensive preventive measures in the future.