A chemical method of iodine atoms generation based on NCl3 is proposed. Iodine atoms are generated by the reaction of iodine donors with chlorine atoms produced from the combustion of NCl3. A chemical model for NCl3/I2 reaction system is developed. Simplified one-dimensional numerical simulations are carried out with a developed Matlab code. The results indicate that the number density and yield of iodine atoms are significantly influenced by the molar flow rate ratio of I2 to NCl3, and the optimum ratio decreases with the total pressure. The optimum yield of iodine atoms decreases with the total pressure, which indicates that this method favorites direct injection into the main gas flow to produce iodine atoms. The optimum ratio of I2 to NCl3 is 0.62 at the pressure of 666.61 Pa with iodine atom yield of 117% versus NCl3 and 189% versus I2. The modeling results show that the NCl3/I2 reaction system is an effective method to produce iodine atoms.