Abstract: The bundle hybrid offset riser (BHOR) is a slender marine structure, it is efficiently and accurately to use the beam model instead of solid model in strength analysis. Consideration is given to efficiency and accuracy through a technique in which the global response of BHOR is simulated based on beam model and the local response of the dangerous position based on solid model. the equivalent inertia moment calculation method of BHOR is given by theoretical derivation. The equivalent polar moment of inertia is calculated based on numerical simulation. The equivalent mechanical properties of BHOR are given to the beam element, and the overall response is simulated and the dangerous position is determined. The numerical simulation is carried out for the dangerous position using the solid element, and the stress distribution of the local model is obtained and the strength check is performed based on the specification. The method takes into account the calculation efficiency and precision, and provides an effective means for the analysis of the mechanical properties of BHOR.