The invention discloses an air cooling segment structure of a horizontal annealing furnace. The air cooling segment structure of the horizontal annealing furnace comprises a furnace body. Furnace rollers of the same height are arranged in the furnace body and hold up strip steel. Air nozzles are symmetrically arranged on the upper and lower sides of the furnace rollers and connected with cooling fans. The air nozzles comprise spraying pipes and spraying openings, and the spraying openings are outlets which are formed in the spraying pipes and face the strip steel. Each set of air nozzles comprises a plurality of sets of spraying pipes. Waste discharge fans are arranged on the upper portion of the furnace body, and air flues of the waste discharge fans are communicated with a flue gas treatment device. The interior of the furnace body is divided into a plurality of air cooling segments through partition plates. The air cooling segment structure of the horizontal annealing furnace has the beneficial effects that by designing the four continuous air cooling segments, the temperature of the strip steel can be rapidly lowered to achieve rapid cooling, and it can be avoided that the strip steel is broken due to cold brittleness; and meanwhile by using steel for making the transfer rollers in the furnace body, damage to roller surfaces can be prevented on the premise of guaranteeing board surface quality.