Abstract: Following a severe accident in a nuclear reactor, the efficient removal of radioactive iodine vapor from the containment atmosphere is critical for mitigating radiological consequences and ensuring nuclear safety. Iodine, particularly in its elemental form (I₂), poses a significant threat due to its high volatility, fission yield, and biological hazard to the thyroid. Spray system is a primary mitigation strategy, relying on gas-liquid heat and mass transfer coupled with chemical reactions to capture iodine. Systematic spray removal experiments were conducted using a self-developed comprehensive experimental facility designed to simulate iodine vapor behavior inside a containment vessel. In the 0.2 m³ facility, spray parameters were precisely controlled, and temperature and pressure dynamics were monitored in real time. The effects of key parameters on iodine vapor removal efficiency were systematically investigated, including spray flow rate (90-133 L/h), spray angle (45°-120°), initial iodine concentration (2.5-5.0 g/m³), spray solution pH (8.1-14), and solution type (sodium thiosulfate, sodium hydroxide, boric acid, and process water). Iodine concentrations were accurately measured using inductively coupled plasma mass spectrometry (ICP-MS). The results demonstrate significant thermal-hydraulic responses during spraying. With an initial gas-phase temperature of 130 ℃, the first spray injection causes a sharp pressure peak of 0.33 MPa due to rapid flash evaporation, while the pressure stabilizes at 0.15 MPa by the end of the experiment. Increasing the spray flow rate from 90 L/h to 133 L/h enhances removal efficiency from 62.6% to 78.0% due to improved droplet distribution and interfacial area. Similarly, enlarging the spray angle from 45° to 120° expands spatial coverage and increases liquid residence time, boosting removal efficiency from 60.5% to 68.1%. Alkaline conditions favor iodine absorption, and increasing pH from 8.1 to 14.0 raises removal efficiency from 71.7% to 85.4%. Among the solutions tested, 1% sodium thiosulfate (Na₂S₂O₃) achieves the highest removal efficiency of 90.1%, attributed to its irreversible redox reaction with iodine, outperforming NaOH, boric acid, and process water. This study provides quantitative insights into the synergistic effects of thermal-hydraulic and chemical parameters on iodine spray removal. The findings offer a robust experimental basis for optimizing containment spray system design and operational strategies under severe accident conditions, thereby enhancing the management of radioactive iodine release risks.