The invention relates to the field of rotary kiln equipment, and discloses a rotary kiln high in heat energy efficiency. The rotary kiln comprises a kiln body, a kiln head cover and a kiln tail cover,the kiln body is of a sleeve structure and comprises an outer cylinder, an inner cylinder and a combustion chamber, the outer cylinder and the inner cylinder are coaxially and fixedly arranged, and the combustion chamber is located between the outer cylinder and the inner cylinder; the outer cylinder and the inner cylinder are mutually supported and connected through a pipeline, and a material ofthe outer cylinder is conveyed to the inner cylinder through a pipeline; a feed inlet is formed in the portion, close to one end of the kiln body, of the outer cylinder; the portions, close to the other end of the kiln body, of the outer cylinder and the inner cylinder are provided with an outer cylinder discharge port and an inner cylinder discharge port respectively; the two ends of the combustion chamber are provided with an air inlet pipe connected with an air source and an air outlet pipe for discharging waste gas, and a heat exchange device is arranged between the air inlet pipe and theair outlet pipe.