Abstract: The traditional oil storage methods have bottlenecks such as large land occupation, high cost, and significant safety and environmental risks, and is difficult to meet the increasingly growing demand for oil reserves at present. This paper innovatively proposes the technology of flexible oil storage in waters. By replacing geological support with water body support and rigid storage tanks with flexible oil bladders, it breaks free from resource constraints through water buoyancy and internal and external hydraulic pressure self-balancing characteristics, establishing water-based reserve bases with advantages of water reserves potential development, land conservation, high safety, flexible storage, and wide adaptability. The research background, innovative concepts, technical advantages, key technological breakthroughs and engineering application prospects of the technology is reviewed in this paper. Its core technical points in pollution prevention and control, device design, and operation and maintenance support is discussed. And its industrialization development and engineering demonstration directions is prospected. The research aims to provide theoretical reference and technical support for the diversified construction of China's petroleum reserve system and energy security guarantee.