An annular-gap-type gas supply element, characterized in that it comprises a central pipe , an inner sleeve , an outer sleeve , an outer gas space and an inner gas space located in the outer gas space, wherein the inner sleeve is set on an outer peripheral surface of the central pipe , and the outer sleeve is set on an outer peripheral surface of the inner sleeve ; at least one inner annular gap is formed between the central pipe and the inner sleeve , and at least one outer annular gap is formed between the inner sleeve and the outer sleeve , wherein the at least one inner annular gap is connected with the inner gas space, and the at least one outer annular gap is connected with the outer gas space; wherein the inner gas space comprises an inner gas chamber and a central overflow plate arranged in the inner gas chamber , and the central overflow plate is provided with central overflow holes; the central pipe is erected on the central overflow plate , and the inner sleeve is erected on the inner gas chamber ; and the outer gas space comprises an outer gas chamber , and the outer sleeve is erected on the outer gas chamber ; wherein the inner gas space further comprises inner diversion parts which are arranged at an end of the inner gas chamber near the inner annular gap(s) , through which an inner gas is guided to the inner annular gap(s) ; wherein guide surfaces of the inner diversion parts are spiral conical, wherein the guide surfaces of the inner diversion parts refer to the surfaces where the inner diversion parts contact with the inner gas; and wherein the outer gas space further comprises outer diversion parts which are arranged at an end of the outer gas chamber near the outer annular gap(s) , through which an outer gas is guided to the outer annular gap(s) . at least one inner annular gap is formed between the central pipe and the inner sleeve , and at least one outer annular gap is formed between the inner sleeve and the outer sleeve , wherein the at least one inner annular gap is connected with the inner gas space, and the at least one outer annular gap is connected with the outer gas space; wherein the inner gas space comprises an inner gas chamber and a central overflow plate arranged in the inner gas chamber , and the central overflow plate is provided with central overflow holes; the central pipe is erected on the central overflow plate , and the inner sleeve is erected on the inner gas chamber ; and the outer gas space comprises an outer gas chamber , and the outer sleeve is erected on the outer gas chamber ; wherein the inner gas space further comprises inner diversion parts which are arranged at an end of the inner gas chamber near the inner annular gap(s) , through which an inner gas is guided to the inner annular gap(s) ; wherein guide surfaces of the inner diversion parts are spiral conical, wherein the guide surfaces of the inner diversion parts refer to the surfaces where the inner diversion parts contact with the inner gas; and wherein the outer gas space further comprises outer diversion parts which are arranged at an end of the outer gas chamber near the outer annular gap(s) , through which an outer gas is guided to the outer annular gap(s) . <EOS>