Abstract: To validate the absorption efficiency of sodium hydroxide (NaOH) solution for chlorine (Cl₂) in the exhaust gas of a chemical oxygen-iodine laser (COIL), this study constructed a simulated experimental platform for laser exhaust treatment. Systematic investigations were conducted to elucidate the effects of key parameters including nozzle spray angle, number of spray sections and nozzles, nozzle spray pressure, and NaOH solution concentration on Cl₂ absorption performance. Experimental results show that under identical operating conditions, the absorption efficiency is relatively better when the nozzle spray direction is 180\text° relative to the gas flow direction, which is consistent with the numerical simulation results; when the spray pressure reaches a critical threshold, further increase in pressure yields no significant improve-ment in absorption efficiency; within a specific concentration range, increasing the NaOH solution concentration conversely leads to a decline in the absorption efficiency; under the same flow rate conditions, increasing the number of spray sections significantly enhances the overall Cl₂ absorption efficiency. This study provides critical theoretical insights and data support for the subsequent engineering development of COIL exhaust treatment devices.