Abstract: This paper was based on the catalytic activity of I- in color increasing reaction in which KIO4 oxidiaed in briｇht green (sf),so as to establishe a new ,high sensitive and high selective method of assaying I2 content in salt by catalytic dynamics photometric method.Linear assaying range was 0.5～12.5μg/25ml and measuring limit was 2.9×10-1μg/ml.Repetition of this method was fine accurate and operation simpler and process prompt.The satisfactory effects were obtained.

Key words: Catalytic , Kinetic spectrophotometry , Iodine , Salt.