The invention provides a cooling air supply device for a cold-
strip steel continuous annealing furnace. The cooling air supply device for the cold-
strip steel continuous annealing furnace comprises a
water cooled heat exchanger, and a circulating fan, wherein the outlet of the
water cooled heat exchanger is connected with the inlet of the circulating fan through a front pipeline of the circulating fan; the outlet of the circulating fan is connected with a blowing cooling bellow inside the annealing furnace body through a high-
hydrogen protective gas injection pipeline; the inlet of the water-cooled
heat exchanger is connected with an exhaust port of the annealing furnace body through a protective gas extracting pipeline; a negative pressure-proof pipeline is arranged between the outlet and the inlet of the circulating fan; and the flow direction of the gas in the negative pressure-proof pipeline is the direction from the outlet of the circulating fan to the inlet of the circulating fan. By using the device, leakage of high-
hydrogen concentration gas is reduced to the maximal extent by matching with a few of detecting instruments;
energy consumption is reduced; expenses are saved; the
operational safety of personnel around a circulating air duct is ensured; the chance that the air enters inside the air duct is reduced; and the security of high-
hydrogen gas inside the circulating air duct is increased.