Abstract: This paper is based on the configuration characteristics and topographical changes of the seabed landslide and the results of geophysical exploration and engineering geological prospecting. The structural deterioration characteristics are recognised. A comprehensive analysis of the sliding mechanism is carried out using the following factors: topography, stratum, hydrodynamic conditions and the landslide structure. For different landslide factors, different stability evaluation methods are adopted n. For the submarine landslide, the limiting equilibrium method is adopted; for the posterior landslide, the arc slice method is used. The parameters of the undisturbed and remoulded soft soil samples taken from the submarine landslide are used in calculation. It is found that this submarine landslide was caused by the integrated effect of natural geology, human activity, gravitation and ocean dynamics. The stability factor is far below 1. The findings provide a qualitative and quantitative scientific basis for the landslide remediation.