The disadvantages of traditional iodine generator are that it costs more preparation and the flowrate of iodine descended visibly in long-time operation. The well-distributed vanes in the cryosorption iodine generator enlarge its specific surface and conduct energy well, which are the preconditions of steady iodine supply. The cryosorption iodine generator at liquid nitrogen temperature can also be used to capture the residual gases consequently to realize closed equipment through which the raw materials circulate. The method of two-wavelength absorption spectroscopy is used to measure the flowrate of iodine, which can eliminate the influence of scattering in the mirrors and monitor the flowrate accurately and timely.