Abstract: Against the calculation demand of bearing capacity for high-power offshore wind power supporting structures exposed to complex loads, the axial compressive capacity formula for tapered concrete-filled double skin steel tubular (TCFDST) members was derived from the elastic-plastic solution of thick-walled cylinders based on the unified strength theory (UST), in which the influence of varying intermediate principal stress coefficients (IPSC) on axial bearing capacity was revealed under the key parameters, e.g., taper degree, hollow ratios, and diameter-to-thickness ratios, so that to provide the reasonable values of IPSC. The limit state method for calculating the bending capacity of TCFDST members was proposed based on the cross-sectional load balance; and the calculation applicability on N-M correlation curves obtained from the limit state method and the modified compression-bending capacity equations based on the code (T/CCES 7−2020), was analyzed. Based on the UST, the layered integral method suitable for the torsional capacity of TCFDST members was derived, and the relationship between the N-T correlation curves based the UST with different values of IPSC and those using the modified code-specified (T/CCES 7−2020) method based on Von Mises yielding criterion was analyzed. A 3D surface equation of compression-bending-torsion capacity for TCFDST members was thereby established upon the compression-bending-torsion numerical analysis results that included various axial compression ratios and torsion ratios, where the function relationships between equation coefficients and hollow rate, taper degree and slenderness ratio were determined. The accuracy of existing methods in the literature was comparatively analyzed. The results of this paper can provide useful references for the application of TCFDST members to wind power project.