Abstract: Based on the removal of gas methyl iodide by containment filter venting system, the alkalescent sodium thiosulphate solution was used as the absorber to study the characteristics of the absorption process with experiments. The results show that the temperature of solution, system pressure, gas flow rate and the height of liquid are important factors to influence the gas methyl iodide removal efficiency. The influence of temperature present a regional effect, in the range of 0~80℃, the removal efficiency increases obviously along with the improved temperature, while the chemical reaction process is a major factor that limiting the removal efficiency. When the temperature is higher than 80℃, the efficiency is no longer sensitive to the variation of temperature and the mass transfer process becomes the main limiting factors. The increase of system pressure or height of solution can enhance the gas absorption process significantly, and the removal efficiency improves linearly with two parameters. However, the gas volume flow rate plays an opposite role on the absorption process. In addition, the variation of entrance concentration has a little impact on the removal efficiency.