Abstract: In the process of offshore drilling and production, the subsea wellhead system is the basis for drilling and production facilities and equipments. Its fatigue life is quite important. With "KAN TAN 3" platform as the hypothetical platform, taking some oilfeld in the South China Sea as an engineering example, the mechanical analysis model of riser was completed using software MOSES, and the force of flexible joint at the bottom of riser was calculated. Then ABAQUS fnite element analysis software ABAQUS was used to establish the fnite element model of the subsea wellhead system. The interaction between soil and subsea wellhead system was simulated based on the nonlinear spring of ABAQUS according to the P-y curve of the soil in the study area, and its fatigue life was calculated. The results show that fatigue life of the designed subsea wellhead can meet relevant specifcations and design and application requirements on the subsea wellhead of DNV codes.