Abstract: In order to investigate the influence of jets width on detonation initiation via imploding annular shock waves, detonation initiation with different jets width were simulated and hydrogenair mixture was used. The results indicate that when jets temperature is constant, different jets width exist different critical jets pressure, when jets pressure Pin is higher than the critical jets pressure, imploding annular shock waves can form high pressure and high temperature region that lead to direct initiation; the critical jets pressure increased with the increase of jet width.