The triboelectric nanogenerator (TENG) technology is rapidly becoming a promising candidate for harvesting wave energy from the ocean. In this paper, through an in-depth analysis of the working principle of spherical TENGs, for the first time, a dynamic model of this structure is proposed based on a cylinder-cylindrical shell configuration, and integrated into TENGs electric model. We verified the assumption that the motion of internal ball of the spherical TENGs is a small oscillation by comparing the V-Q-x relationship with experiments. The model reveals the influence of structural/material parameters, such as the radius of inner ball, density of material, and thickness of the shell on the energy output of TENGs. The results show that the change of the radius of the inner ball plays the dominant role on the power output with the other two parameters affecting the power output level of the TENG to varying degrees. These structural/material parameters can be combined to optimize and increase the output performance of spherical TENGs.