Abstract: A theoretical model of dynamicequilibrium iodine supply system was built. An iodine supply system for COIL based upon that model was designed, which has only 1/8 volume, 1/3 weight, and takes half the time to preheat as the conventional staticcapacity iodine supply system does. Experimental results show that the stability of the system is reliable, especially for a long operation; and iodine flow rate can be conveniently adjusted in a wide range. With these merits, it meets the need of experimental optimization of iodine flowrate for COIL.