Submarine power cables are critical components of infrastructure that facilitate the interconnection of offshore energy resources. During their operational lifespan, these cables may become suspended due to ocean current scouring and seabed erosion. The behavior of spanning submarine power cables under dynamic bending loads is characterized by varying degrees of contact and slip between structural layers, leading to nonlinear bending responses. This phenomenon presents significant challenges for analyzing bending behavior and predicting fatigue life. This paper establishes a nonlinear finite element model for submarine power cables, initially assessing their bending stiffness under pure bending loads. The model’s validity is confirmed through four-point bending prototype tests. Furthermore, the model delineates the response of spanning submarine power cables subjected to combined tension and bending loads, examining the influence of structural design parameters of the tensile armor layer on nonlinear bending behavior. The findings reveal that increased tension and the friction coefficient between the tensile armor layers elevate the initial critical curvature for partial sliding, thereby enhancing the bending resistance of the spanning submarine power cables. Conversely, an increase in helical winding angles result in a reduction of bending stiffness in the initial phase. These parameters must be carefully considered in the structural design and engineering applications of spanning submarine power cables to effectively address their nonlinear bending behavior.