Abstract: Detonation characteristics of several fuel vapor (propylene epoxide, IPN,C5~C6, hexane, heptane, decane)-air mixtures were studied. Critical initiation energy was measured by the up-and-down method and cell size on soot foil. Results demonstrate that the relationship of critical initiation energy and equivalence ratio shows a U-shaped curve, the critical energy is obtained when equivalence ratio is slightly larger than 1. Meanwhile these results are used to calculate theoretical critical initiation energy of hydrocarbon-air mixture in unconfined conditions, and calculated values agree well with experimental results. The comparison of detonation characteristics among these fuels indicates that detonation of FAE in low fuel vapor pressure is similar to the gaseous detonation. These experimental results enable us to have an insight into the detonation nature of fuel-air mixtures.