Experiment and simulation were conducted to study the development process of jet fire and explosion induced by the high-pressure hydrogen spontaneous ignition. The pressurized hydrogen was released under different tube length and release pressure in the experiment. The overpressure generated by the leading shock and the light signal of the flame with different conditions were recorded. The propagation of the external jet flame was captured by a high-speed camera. Different parameters including velocity, temperature, and concentration distribution were analyzed based on the simulated results. It is revealed that the jet fire and explosion, which are induced by hydrogen self-ignition, must go through a series of specific stages of development, and this process has no significant correlation with pipe length and release pressure. This process consists of several stages, including the formation of the combustion zone downstream of the Mach disk; the flame chases the top of the jet along the shear layer; the flow velocity at the top of the jet decreases causing the ring vortex to disappear and the combustible gas to accumulate; the shear layer flame propagates to the top of the jet causing the explosion. Besides, the explosion will inevitably occur along with the jet fire, which is caused by the spontaneous ignition induced by the sudden release of high-pressure hydrogen and is developed in the open space. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.