In order to investigate the pulse laser action process of the explosives doped with nano-aluminum powder， the plasma expansion and shock wave characteristics of single-pulse laser ablation of the PETN explosives doped with 1% nano-aluminum powder were studied by shadow measurement system， while the characteristic spectra of the explosives after laser ablation were investigated by laser induced breakdown spectroscopy （LIBS）. The results showed that when laser pulses irradiate the surface of PETN explosive doped with nano-aluminum powder， high temperature and high density plasma was formed， which expanded continuously and compressed the surrounding air to form shock wave. At 50 ns， the velocity of shock wave was 12500 m•s^-1. With the increase of time， the plasma continued to expand， the shock wave advanced forward and the velocity decreased. At 800 ns， a large number of ejection materials were observed in the shock wave. The maximum strength of the spectral lines of Al atom and AlO gas phase molecule were achieved at 1 μs， and disappeared at 10 μs， indicating that the interaction time between nano-aluminum powder and explosive was less than 10 μs. The spectral lines of C atom and CN were not detected at 20 mJ laser energy. When the laser energy increased to 30 mJ， the spectral lines of C atom and CN group were observed in the spectrum of PETN explosive doped with nano-aluminum powder， and the spectral intensity increased with the increase of laser energy. Moreover， the laser energy required for the decomposition of the PETN explosives doped with nano-aluminum powder should not be less than 30 mJ.