Zirconium powder, a main potential dangerous source in nuclear industry, has been focused on its explosion characteristics in this paper. Experiments were performed in a 20 L cylindrical explosion vessel with the influences of initial ignition energy, ignition delay time and zirconium concentration. Results showed that the maximum explosion pressure of zirconium-air mixture rose with the increase of the initial ignition energy, and a peak value was obtained with the variation of the ignition delay time. Lower explosion limit with the initial ignition energy of 10 kJ is 10 g/m(3). Furthermore, explosion severity parameters, including maximum explosion pressure, maximum rate of pressure rise and maximum explosion index of zirconium-air mixture, were also obtained with the coupling variation between initial ignition energy and dust concentration. Research results and data obtained are a supplement to the utilization and safety operation of zirconium powders. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.