Abstract: Though a lot of study has been carried out on hydrogen-air rotating detonation engine, combustion technologies are still difficult due to the difficulty of mixing for hydrocarbon fuels and air. Rotating detonation waves in an optically accessible combustor with a wide observation window have not been studied in China. Ethylene or hydrogen air-brathing rotating detonation tests with inlet total temperatures 283~284 K were conducted in the present study. The detonation channel of the hollow combustor has an outer diameter of 100 mm and a length of 151 mm. Fuel and air were injected into the combustor from 150 cylindrical orifices of a diameter of 0.8 mm and a convergent-divergent circular channel with a throat width of 1 mm, respectively. A piece of quarts glass of 140° was mounted in the outer wall of the combustor to observe the detonation wave. High-speed imaging and pressure traces both proved the detonation speeds. The hydrogen detonation speed could be as high as 101% of CJ values and the pressure gain is as high as 40%. The ethylene detonation speed was up to 89% of the theoretical value. The detonation structure is changeful and irregular. Hydrogen-air rotating detonation sustenance is easier than hydrocarbon-air one. Hydrogen detonation is more stable than ethylene one.