In this paper, the internal mechanism of solid deuterium spatial distribution induced by infrared radiation is studied. The changes in spatial distribution and micro-structure of solid deuterium are also discussed as the results of wavelength and heating time of IR light. It is found that the micro-structure of solid deuterium which is irradiated by a special IR light is changed from polycrystal to monocrystal, the solid deuterium is redistributed and becomes more uniform and transparent. The best wavelength of IR light for heating solid deuterium is 3140 nm. When the output power of 3140 nm IR light is 100 upW, the redistribution time of solid deuterium is about 18 min.