This paper presents a numerical method to compute CAD surface models. The method first divided a CAD model into a sequence of subfields, each of which is a simple surface-patch of the CAD model. Then, by setting up the governing equations for the patch-element, it computed the total field by assembling governing equations of all subfields into the global equations of the total field according to the manifold structure of the CAD model. The element's governing equations can be formed by coupling finite element (FE) with boundary element (BE), and FE with element free (EF) or else according to the objective of the computed problems. The paper systematically demonstrates the key procedures of selecting elements and setting up governing equations via a solution process of linear elastic problems. A numerical example with comparison to ANSYS computation is shown in the analysis of deformation on a blending surface of three-rounded corner. Finally the static loads are presented before the paper comes to an end.