Damage of dimethyl methyl phosphonate (DMMP) under shockwave pressure induced by explosive detonation was studied. The decomposition of DMMP sample impacted by shockwave was mensurated quantitatively by gas chromatography,and the sample component was analyzed by gas chromatography-mass spectrograph. Results show that the DMMP impacted by high pressure decomposes partly,and the DMMP content is reduced from 93.81% to 84.77% with increasing of the pressure in the range of 12.24-22.41 GPa.