The invention discloses a dry method dedusting air supply method and a dry method dedusting air supply system, and belongs to the technical field of dedusting. The method includes the following steps: confirming blast furnace air supply volume according to blast furnace volume and discharging capacity of a fourth blow off valve; opening the fourth blow off valve, supplying air for a blast furnace, then closing a second blow off valve, a third blow off valve and a first blow off valve in sequence, and enabling coal gas of an air supply initial stage to release heat through the fourth blow off valve so as to preheat a whole coal gas pipeline system; and opening a dry method deduster to conduct dedusting process. The dry method dedusting air supply system comprises the first blow off valve, the blast furnace, the second blow off valve, a gravity deduster, the third blow off valve, a temperature sensor, the dry method deduster and the fourth blow off valve. According to the dry method dedusting air supply method and the dry method dedusting air supply system, the problems that coexistence of the drying method and a wet method is great in investment, much in land occupation and the like are solved, quick air supply after blast furnace maintenance is achieved, blast furnace smelting process is strengthened, production efficiency is improved, coal gas diffusion is reduced, and environment pollution is reduced.