Abstract: Based on the transverse flow characteristic of supersonic chemical oxygen iodine laser gain medium, the optical resonator with gain negative feedback structure has been designed. Through coupling simulation of the chemical reaction supersonic flow field and light field, and depending on the laser operation parameters, the feasibility of this structure to realize the pulse laser has been demonstrated. The results show that when the oscillation laser in the gain area upstream is amplified the more times and energy extraction ability for the upstream gain medium is stronger, the pulse modulation effect is more significant. Using structural design that the laser spot is narrowed and then expanded, the peak power of the pulse laser will increase 10 to 20 times, which theoretically proves the modulation method of the gain negative feedback can realize the transverse flow laser with the pulse laser output.