The double-layer oil tank, as a key equipment in the modern oil storage field, contains many exquisite features in its structural design. Taking the common SF double-layer oil tank as an example, the inner layer is made of 6mm thick Q235-B steel plate. Compared with the 5mm thickness of ordinary single-layer oil tanks, the strength is significantly improved, which can better withstand the pressure of the stored liquid. The outer layer is a reinforced glass fiber layer with a thickness of over 2.5mm, which not only has excellent compressive and seismic performance, but also has good corrosion resistance and electrical corrosion resistance. There is a 0.1-3.5mm through gap between the inner and outer layers, which provides additional assurance for the safe operation of the oil tank. Once the inner tank leaks, the leaked liquid or gas will enter the gap space instead of directly leaking into the external environment. At the same time, the equipped leak detector can monitor the liquid level at the bottom of the gap space in real-time 24 hours a day. Once the liquid level changes, an alarm will be immediately issued, greatly improving the safety of the oil tank. This double-layer structure design fundamentally reduces the risk of oil storage and is an important foundation for the widespread application of double-layer oil tanks.