The invention relates to the technical field of the lime kiln and discloses an air supply system for the lime kiln. The air supply system comprises an exhaust fan, an air supply pipeline and an air collection tank, the exhaust fan is fixedly connected with the air supply pipeline, the air collection tank is ring-shaped, the air collection tank and the air supply pipeline are fixedly connected, three air supply branch pipes are formed in the ring-shaped inner wall of the air collection tank, the included angles among the three air supply branch pipes are 120 degrees, and an air cap is arrangedon the intersection part of the other ends of the three air supply branch pipes. The air cap is in a tower-shaped structure, the diameters of the multiple layers of the tower-shaped structure are thesame, a plurality of air supply holes are evenly distributed at each periphery of each layer of the air cap, and a plurality of air outlets are evenly distributed at the periphery of each layer of theair cap. The air cap is in the tower-shaped structure, and the diameters of the ten layers of the tower-shaped structure are the same. A dust falling groove is distributed at the top part of the aircap, and a dust leading pipe is distributed at the lower part of the air cap. The air supply system overcomes the defect of uneven air supply of the lime kiln existing for a long period of time.