The wet materials are sent to the hopper by a belt conveyor or bucket elevator, and then enter the feeding end through the feeding pipe of the feeding machine of the hopper. The inclination of the feeding pipe should be greater than the natural inclination of materials to facilitate materials to flow into the dryer smoothly. The dryer cylinder is a rotating cylinder which is slightly inclined with the horizontal line. Materials are fed in through the higher end, and heat carrier enters through the lower end contacting with materials in counter-flow. Sometimes the heat carrier and materials flow into the cylinder together. As the cylinder rotates, the materials move to the lower end due to gravity. When the wet materials move forward in the barrel, they receive the heat from the heat carrier directly or indirectly, and the wet materials dry. Then, the wet materials are sent out through the discharge end through a belt conveyor or screw conveyor. The inner wall of the barrel is equipped with a lifting flight, which can lift the materials and scatter them, increases the contact surface of the materials and the airflow, in order to improve the drying rate and forward the materials advancement.