As an important organic raw material, formaldehyde is also a raw material for dyes, medicines, and pesticides, as well as fungicides and disinfectants. Because formaldehyde can cause pollution, it is harmful to the environment. Therefore, the liquid level of the storage tank needs to be monitored in real time in actual working conditions. According to the specifications, corresponding alarms and interlocks need to be set. However, because of the easy polymerization of formaldehyde, the original formaldehyde tank liquid level detection instrument cannot accurately measure its liquid level. Therefore, in view of the liquid level measurement of formaldehyde tank, the application of several common liquid level measuring instruments were introduced in turn from the aspects of measurement principle, advantages and disadvantages. It is hope to provide certain technical support for the design institute and formaldehyde tank user enterprises.