Abstract: Zirconium powder is widely applied as high-energy fuel for it has not only a faster burning speed but also a stronger burning heat. Flame comes into being from the combustion of zirconium dust cloud with a lot of zirconium particles suspending in the air. A transient flame propagation experimental system was established to study the flame temperature and flame propagation speed characteristics of zirconium dust cloud in a vertical pipeline. The results indicate that the maximum flame temperature and the maximum flame propagation speed of zirconium dust cloud have the same changing trend at thermocouple positions, i. e., both their values increase firstly and then decrease with the increasing concentration of zirconium dust cloud. The maximum flame temperature reaches 1777.81℃and the maximum flame propagation speed is up to 39.7 m·s^-1 when the concentration of zirconium dust cloud at 0.625 kg·m^-3. But when the concentration exceeds 0.625kg·m^-3, both the maximum flame temperature and the maximum flame propagation speed decrease. The main reason is that zirconium particles occur incompletely burning owing to rich fuel combustion in the pipeline.