An iodine analysis instrument with sequential injection of urine samples was developed. A method for measurement of urine iodine was also developed by combining sequential injection and catalysis kinetics,and making use of catalysis facilitation of the iodine in the redox reaction of As~(3+) and Ce~(4+) . The sequential injection and stopped-flow stabilization determination were made possible by the program-controlled injector with controlled flow rate and the 16-hole program-controlled selection valves. The arsenic-cerium reaction with iodine-catalyzed at constant temperature state might proceed with the constant temperature flow cell. Using the syringes with program-controlled velocity,pushing and suction,Using the digital connected circuit and micro-iodine determination software,the reaction temperature of (32.0±0.1)℃,injection time of 45 s,stabilization time of 60 s,detection time of 20 s,injection volume of 400μL,linear range of 15 -600μg/L,detecting limitation of 5.01 μg/L(n=11) and recovery rate of 94. 1 % - 105. 1 % were obtained. With this method,the detecting result of the National Standard Reference (GBW09109 and GBW09110) materials was within a given standard range. Through this method,the detecting results had no significant differences comparing with those by standard method of National Health Service(P >0.05).