The invention relates to a rotary kiln with a power generation device. The rotary kiln comprises a power generation device, a material loading device, a material bin, a kiln body, a kiln end cover, a cooler and a cooling fan. A kiln head is provided with a burner; the kiln body is composed of an inner cylinder and an outer cylinder structure, a kiln chamber is in the middle of the inner cylinder, an annular space formed between the inner cylinder and the outer cylinder is a material chamber, and the annular space is provided with a support column; the rotary kiln is provided with a screw conveyor, a discharge passage and a gas collecting tube; the material loading device is connected with the material bin, the material bin is connected with the annular space through the screw conveyor, and the annular space through the discharge passage is connected with the cooler; and the lower part of the cooler is connected with a discharge hatch, the upper part of the cooler through the kiln head is connected with the kiln chamber, and the kiln chamber is connected with the power device. Through the kiln body with the inner cylinder and outer cylinder structure, limestone in the annular space is heated through flue gas dividing wall, so as to avoid direct contact of the flue gas with the material and benefit utilization and recovery of decomposed carbon dioxide gas; and at the same time, and waste heat of flue gas is utilized for power generation, so as to reduce the energy consumption of the rotary kiln.