Phosphate ore decomposed by nitric acid is an important operating unit in the process of nitrophosphate produc-tion.The effects of acid hydrolysis time of 30~240 min,temperature of 40~90 ℃,nitric acid initial mass fraction of 40%~65% and acid to phosphate ore mass ratio of 1.15:1~1.35:1 on the migration and distribution of iodine in phosphate ore for gas,liquid and solid phases were studied.The results showed that in the decomposition process of phosphate ore by nitric acid,iodine transferred to the gas phase in the form of elemental.The distribution rate of iodine in gas phase increased with the increase of acidolysis time,temperature and nitric acid initial concentration.However,with the increase of mass ratio of acid to phosphate ore,iodine in the gas phase first increased and then decreased.The distribution rate of iodine in gas phase was more affected by acid hydrolysis time and temperature than by other parameters.When the process parameters were controlled at the acidolysis temperature of 60 ℃,nitric acid initial mass fraction of 55%,acid to phosphate ore mass ratio of 1.25:1 and acidolysis time of 120 min,the distribution rate of iodine in the gas phase was 65.21%,the distribution rate in the liquid phase was 26.89%,and the distribution rate in the solid phase was 7.91%.