The invention relates to a sliding arc plasma combustion-supporting exciter without relying on external gas supply of a combustion chamber. An electrode mounting seat is installed in an anode casing pipe; and an inner annular cavity is formed between the outer surface of a cathode cone connecting section at the lower end of the electrode mounting seat and the inner surface of the anode casing pipe. One end of a cathode electrode rod penetrates through the electrode mounting seat to be connected with a cathode cone. An outer annular cavity is formed between the inner circumferential surface ofan outer ring cavity sleeve and the outer circumferential surface of the anode casing pipe. The outer ring cavity is in communication with the inner ring cavity through inner layer air inlet holes located in the anode casing pipe. The inner layer air inlet holes are axially distributed in the pipe body of the anode casing pipe. According to the sliding arc plasma combustion-supporting exciter, two-strand channel gas of the combustion chamber serves as a working medium gas, the technical bottleneck that an existing plasma combustion-supporting technology is not good for improving the performance of the combustion chamber is broken through, and the sliding arc plasma combustion-supporting exciter has the characteristics of being simple in structure, suitable for conversion and application inthe field of combustion of aviation engines and strong in universality.