Abstract: To safely recover the waste heat of the converter gas, a series of experiments were conducted to explore the deflagration properties of CO-air mixture at different initial temperatures in a duct lined with obstacles. By measuring deflagration pressure and flame speed, influences of CO stoichiometry and temperature on deflagration properties were investigated. Results show that the pressure and flame speed increase rapidly in the duct segment lined with obstacles. When CO stoichiometry is 1.100, deflagration attains the maximum intensity. As the initial temperature increases, the pressure increase slows down, and the maximum flame speed decreases,but still keeps a high speed, over 550 m/s. The flame propagation time increases at first and then becomes stable along with the increasing of the initial temperature.