The invention provides a temperature measuring method for materials in a rotary furnace. The temperature measuring method is characterized in that a thermocouple and a protective pipe extend out of the rotary furnace at the position of a rotary outer wall without a heating jacket, are sealed by flanges and are connected with a wireless temperature transmitter through a signal cable. The wireless temperature transmitter is fixed at a position of a certain distance on the rotary outer wall of the rotary furnace through a support and rotates along with the rotary furnace. A temperature measuring probe on the thermocouple collects a temperature data signal, the temperature data signal is connected with the wireless temperature transmitter through the signal cable and transmitted to a gateway through the wireless temperature transmitter, and finally the signal is led to a control system. The control system adjusts the conveying quantity of a furnace externally-loaded hot body according to the received signal to control the temperature of materials of each section in the furnace automatically. By means of the temperature measuring method, the temperature of the materials of each section in the rotary furnace can be measured correctly, the service life is long, the precision is high, and overhauling and replacing are convenient. Effects of thermal expansion of a rotary furnace barrel on a temperature measuring device are eliminated. The rotary furnace adopting the method can greatly improve the product quality, meanwhile effectively reduces energy consumption, and reduces labor intensity of workers.