The invention relates to a cladding structure based on a tantalum board and a steel composite panel. The cladding structure based on a tantalum board and a steel composite panel comprises a panel composite substrate composed of a steel composite board and a tantalum plate (1) covered on the steel composite panel, wherein the steel composite panel comprises a steel layer (2) and a cover layer (3) tiling on steel layer (2); the tantalum plate (1) is laid on the cover layer (3); the lateral side of the tantalum plate (1) and the cover layer (3) are fixed through welding; and the panel composite substrate is provided with a medium flow pipe and/or a reinforcing connection member. The cladding structure can effectively solve the problem that the tantalum pad lining and the steel plate tight lining structure are easy to be damaged, and the whole structure is stable and reliable. A method of processing the cladding structure based on a tantalum board and a steel composite sheet is also disclosed.