In order to evaluate the detonation influence in chemical laser combustor, the detonation from a lasing test in the deuterium fluoride (DF) laser is analyzed in depth. Numerical simulation of the detonation is conducted by the space-time conservation element and solution element (CE/SE) method. The simulation results indicate that the instantaneous pressure in the combustor surges as the detonation takes place and spreads. The vibration, shock and torque acts resulting from the detonation lead to the maladjustment of the lasing resonator, which affects the normal running and lasing of the chemical laser. The results calculated from the simulation will play an important role in guiding the optimized design and the secure running of DF chemical lasers.