To demonstrate the influence of different ignition positions on the explosion characteristics of H2-Air mixtures, a series of experiments at central and end-wall ignition under turbulent and quiescent conditions are carried out in a constant volume spherical container. Three explosion characteristics including explosion time τe, maximum explosion pressure rise rate (dp/dt)max, and maximum explosion pressure pmax are measured and derived from the explosion overpressure curve. The experimental results demonstrate that the explosion hazard with the central ignition is generally stronger than that with the end-wall ignition under quiescent conditions. At lower initial pressure, the difference between two ignition cases is greater. The results show that for central ignition, the energy loss is small, and the explosion behavior is similar to the ideal constant volume explosion. While for end-wall ignition, the interaction between supersonic blast wave and cooling rough wall consumes a large amount of explosive energy. Under turbulent conditions, the increase of the jet pressure pjet and the jet time Tjet leads to the increase of turbulence intensity and duration, which enhances the explosion hazard of central ignition, but restrains the explosion process of end-wall ignition. The difference between the two ignition locations increases with the increase of pjet and Tjet.