A rotary kiln with a high thermal efficiency comprises a kiln body, a supporting device, a combustor, a heat-exchanging settling chamber, a medium chamber, a dust collector, a circulating fan and cooling equipment. A material inlet and a material outlet are formed in the kiln body, the material outlet is connected with the cooling equipment, and the kiln body is further provided with a heating medium inlet and a heating medium outlet; the combustor communicates with the heat-exchanging settling chamber, the medium chamber is arranged at the top of the heat-exchanging settling chamber, and a heat pipe is arranged between the medium chamber and the heat-exchanging settling chamber; a medium outlet of the medium chamber communicates with the heating medium inlet of the kiln body, the heating medium outlet is connected to a medium inlet of the medium chamber through a circulating pipeline, and the high-temperature circulating fan is installed on the circulating pipeline; and a smoke outlet is formed in the heat-exchanging settling chamber, the smoke outlet communicates with the dust collector through a pipeline, and the dust collector is connected with a chimney through an induced draft fan. According to the rotary kiln with the high thermal efficiency, smoke passes through a heat pipe group of the heat-exchanging settling chamber, pure gas in the medium chamber is heated, recycling pyrolysis of materials is achieved, and other impurities cannot be brought in; and the rotary kiln has the advantages that the heat utilization efficiency is high, and the product purity is high.