Abstract: LNG (liquefied natural gas) cryogenic flexible hose is one piece of the key equipment in the process of exploitation, transportation and storage of LNG, which is called as the "blood vessel" of LNG transportation system. With the development of exploitation and transportation of LNG gradually from the offshore to the deep sea in recent years, there is a broader development prospect for LNG cryogenic flexible hose as the core equipment in the LNG transportation system, however, which will face more stringent challenges of structural failures caused by more stringent marine environment at the same time. In this paper, the engineering application background, structural design and internal fluid analysis of LNG cryogenic flexible hose are focused on and the related key technologies are investigated. The research progresses of the above mentioned technologies of LNG cryogenic flexible hose are summarized. Based on the investigations, the flexible structural characteristics of the corrugated structure, the spiral wound structure and the high polymer material in LNG cryogenic flexible hose are classified, the related mechanical mechanism is analyzed and the methods to achieve flexible structural characteristics are summarized. In internal fluid analysis, the responses of calculation and analysis in LNG cryogenic flexible hose are reviewed and combed. In addition, the future research hotspots of LNG cryogenic flexible hose technologies are prospected. The related research work of LNG cryogenic flexible hose technology started relatively late in China, the key technologies of mechanical design and analysis and industrial application of LNG cryogenic flexible hose need to be broken through to improve the ability of domestic design and manufacture of LNG cryogenic flexible hose. It is of great significance to realize independent and controllable key technologies in the development of natural gas resources and to promote the realization of the national strategic goal of "peak carbon dioxide emissions" in China.