Qualified limestone is stored in the silo, lifted by the elevator and transported to the top silo of the preheater. The top bin of the preheater is controlled by two level gauges up and down to control the feeding amount, and then limestone is evenly distributed to each room of the preheater through the feeding pipe. The limestone is heated to about 900°C by the kiln flue gas at 1150°C in the preheater, and about 30% of it is decomposed. The limestone is pushed into the rotary kiln by the hydraulic push rod, and the limestone is decomposed into CaO2 and CO2 by sintering in the kiln. The limestone after decomposition enters the cooler, where it is cooled to below 100°C by the cold air pumped into the cooler and discharged. The hot air of 600°C after heat exchange enters the kiln and gas for mixed combustion. The waste gas enters the cold air through the blower into the bag dust collector, and then enters the chimney through the exhaust fan. The lime from the cooler is fed into the lime product warehouse by the vibrating feeder, the chain plate conveyor, the bucket elevator and the belt conveyor. According to customer requirements to decide if it needs screening and other processes.