The shock sensitivity of sub-micron explosive was studied by small-scale gap test and slapper initiation test; and the shock wave was low pressure-long pulse in the small-scale gap test,and high pressure-burst pulse in the slapper initiation test. The explosive is safe when motivated by a generic environmental force,i.e. low pressure-long pulse and it is sensitive when motivated by special environmental force,i.e. high pressure-burst pulse. Moreover, the shock sensitivity decreases with the reduction of explosive particle size when ignition is a dominant process in the course of shock wave initiation; but oppositely,the shock sensitivity increases when detonation buildup is dominant.