The global and local behaviors of detonation waves are affected by the thermo-chemical coupling process which requires the understanding at molecular level due to its microscopic complexity. In present study, one-dimensional H2-O2 detonation is numerically investigated through DSMC method. The detailed balance between forward and reverse reactions is achieved through a modified reaction model, which improves the simulation accuracy of combustion system. Results show that the overall structure of detonation is in accordance with the CFD result, but the microscopic fluctuation of auto-ignition affects detonation in both initiation and propagation stages. Analysis of the detailed structure in the induction zone shows that the auto-ignition process is strongly coupled with the vibrational relaxation process. The lower vibrational temperature decreases the chemical reaction rates, resulting in an increase of ignition delay time and induction zone length. © 2019 Author(s).