In order to achieve the fusion ignition goal of laser confinement fusion (ICF), the mass of deuterium-tritium ice in the target pellet is required to be more than 99.9%, and the root mean square roughness (RMS) of the inner surface of the ice is better than 1μm. The high quality deuterium tritium freezing target is based on the high quality deuterium tritium ice in the target pellet. Single crystal is the best form of ice, and deuterium-tritium ice seed crystal in target pellet is the basic condition. In this paper, by adopting gradually reduce the temperature controlling method for the steps of heating rate, for the research of the inflatable micro in-pipe preserved seed crystal, reveals the inflatable nucleation mechanism of micro in-pipe preserved seed crystal, the experimental results show that the use of inflatable tube defects can keep stable and single seed crystal, under the same degree of supercooling, when deuterium tritium seed crystal c axis and inflatable tube axial parallel, The growth rate is about 1~2 orders of order slower than that when the C-axis is perpendicular to the axial direction of the gas filled tube. The results provide a reference for obtaining high-quality seed crystals, and provide a basic support for the development of deuterium-tritium refrigerated target in China.