Photolysis of energetic materials offers safer and more controllable advantages compared to traditional ignition methods. Tracking the group and electron dynamics during the photolysis of energetic materials is currently a hot and challenging topic. In this work, we used a time-dependent density functional theory (TDDFT) to study the high-order Harmonic generation (HHG) dynamics induced by strong laser interaction with an isolated CH3NO2 molecule with varying C-N bond lengths. We found that the elongation of the C-N bond leaves a footprint on the corresponding HHG spectrum. One observed phenomenon is that the overall HHG cutoff position increases with the C-N bond length, and another is a sudden decrease in HHG efficiency at a certain bond length. Our analysis shows that this efficiency drop is due to changes in the electron recombination quantum paths caused by the C-N bond length alteration. Our research provides a new approach to tracking the photolysis process of energetic materials.