Abstract: In order to explore the influence of the uncertainty of seismic load and structural resistance on the seismic performance of offshore wind turbine support structure, this paper establishes a simplified nonlinear numerical model of tower-pile foundation-soil by using OpenSEES software. The active learning reliability method based on Kriging Model and Subset Simulation Method（AK-SS） is combined with the Capability Spectrum Method（CSM） to study the reliability changes of support structures under different seismic impact conditions in the service life, and the influence of the thickness, buried depth, diameters, and internal friction angle of sand on structural reliability. The results show that AK-SS is more accurate and efficient than other reliability calculation methods such as Subset Simulation Method（SS）. The mode combined distributed loading mode（SRSS） is suitable for the offshore wind turbine support structure controlled by multiple modes. The rare earthquake condition is the dangerous control condition of the structure, and the mud surface displacement exceeding the critical value is the main failure mode. However, for any failure mode, the structure meets the target reliability requirements before the end of the service period.Compared with the buried depth, the thickness and diameter of the foundation are the control factors of the seismic performance of the structure. The geometric dimension of the pile foundation should be reasonably selected in the design.