In this paper, a three dimensional numerical investigation was carried out to study the formation and propagation characteristics of non-premixed rotating detonation wave using H-2/air as reactive mixtures. At a constant global equivalence ratio, the effects of inlet mass flow rates of H-2 and air on various performance parameters of rotating detonation wave and based on it combustor were analyzed in detail. On this basis, the mode switching process of rotating detonation wave caused by transiently changing the inlet mass flow rates was also discussed. The numerical results showed that inlet mass flow rates of H-2 and air played a very critical role in the formation, propagation and mode switching of rotating detonation wave. With the increase of inlet mass flow rates, rotating detonation wave could be switched from single wave to double waves. The propagation direction of double waves depended on the changing process of inlet mass flow rates. Meanwhile, compared to the single wave, double waves or its based combustor had the obvious advantages in formation time, stability and thrust, but had disadvantage in pressure ratio. In addition, both fill characteristics and mixing quality of fresh reactive mixtures are the underlying important mechanisms to explain the effects of inlet mass flow rates on rotating detonation waves. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.