In this paper, a spherical source distribution method is established, and two kinds of spherical sound sources of symmetric and antisymmetric, distributed on a line inside the structure are proposed, in order to realize the vibro-acoustic calculation of three-dimensional elastic underwater structure. The spherical source distribution method has strong applicability and is suitable for the case where the shape of the structure is not axisymmetric. This method is a new method, and its fundamental formula is similar to the traditional acoustic boundary integral method, but it also has obvious differences. In numerical calculation, the traditional boundary element method is to divide the surface elements on the wet surface of the object, and transform the three-dimensional acoustic problem into the two-dimensional discrete element problem to solve. However, the spherical source distribution method, whose source points are only distributed on a straight line inside the object, transforms the three-dimensional acoustic problem into the quasi-one-dimensional discrete element problem, which makes the complexity and computation amount of the whole programming significantly reduced. In this paper, the fundamental principle of the spherical source distribution method, the calculation formula and the verification results of several numerical examples are discussed.