A drum-type biodrying pilot scale test system was made to treat the municipal sludge. Sludge was mixed with barks according to certain proportion, and was used to study the influence of air flux on municipal sludge biodrying through parameter detection, such as temperature, moisture content, pH and volatile solid (VS). Results showed that air flux had a great influence on the effect of biodrying. When the air flux was 120 L · (h · kg)(-1), the best result was obtained, the highest sludge temperature was 66°C and the temperature could remain upon 55°C for more than 40 h. After 111 h, the moisture content reduced to 56% . The pH remained at 6.5-8.5 through the whole biodrying process. As a result, the microorganism activities would not be affected. The sludge inside the drum-type biodrying system was homogeneous. This research provides a reference about sludge treatment using a continues flow process by drum-type biodrying system.