Study on the phase transition properties and rheological model of submarine sediments during rheological testing is of great significance to the safety assessment for submarine structures. Using the soft clay in South China Sea

five group samples with different water contents were prepared

and a series of rheological tests under different temperature was carried out using the MCR302 rheometer. The results show that shear stress increases rapidly then increases slowly with increasing shear rate

while apparent viscosity decreases rapidly then decreases slowly. The shear stress and apparent viscosity decrease with increase in water content

and they increase with decrease in temperature. Phase transition happens in soft clay during shearing and can be divided into static and dynamic yield stresses

and the models for static and dynamic yield stresses were established on the basis of experimental results. In addition

Dual-Bingham rheological model considering effects of water content and temperature for soft clay from South China Sea was established

and the efficiency of model was verified. The results of this paper can provide basic model for the numerical analysis of submarine structure stability in South China Sea.