It is widely used in urban water supply and drainage, sewage treatment, groundwater, reservoir, river and ocean water level monitoring. On the basis of measuring the liquid phase static pressure proportional to the liquid phase height, the liquid phase static pressure is converted into an electrical signal by using the resistance effect of the diffused silicon sensitive element or the ceramic capacitor element. With temperature compensation and linearity correction, it is converted into a pressure sensor to measure the output liquid level with a standard electrical signal 4-20 mA. The sensing element of the differential pressure transmitter manufacturer can directly input liquid, and the sensing element can be fixed by flange or bracket, which is very convenient to install and use. Using advanced isolation diffusion silicon sensitive elements, the input level is directly placed in the container and the water body, and the water level value of the level is output through 4-20 mA current or RS485 signal to accurately measure the height from the level terminal to the water surface. The design of the water inlet is stable and has high precision. Can be directly placed in the test medium, easy to install and use. The machine has a firm structure, no moving parts, high reliability, long life, water-based and oily forms a high-viscosity paste, and can perform high-precision measurement, which is not affected by the foaming, deposition and electrical properties of the measured medium. It has power supply reverse polarity protection and overload current limiting protection; adopts the characteristics of differential pressure transmitter manufacturers; high-quality sensors have high sensitivity and response speed, can accurately reflect small changes in flowing or static liquid level, and the measurement accuracy high. With the function of safe contact and isolation, it is not subject to external interference, and is suitable for various dangerous places. With an anti-clogging design, it can measure the liquid level of pasty media. The installation is simple, the use is convenient, and it has strong replacement ability. Field reading is very convenient. 6.4-20mA dual-channel signal transmission, with strong anti-interference and transmission distance. 7. Accurate and unique compensation of zero point, temperature drift and nonlinearity ensures the accuracy of the instrument under the conditions of use and long-term stability. 8. Solid structure, moving parts, high reliability and long life. High-precision measurement of pastes with different viscosities such as water and oil can be performed without being affected by the foaming, sedimentation and electrical properties of the medium. The utility model has the reverse polarity protection of the power supply and the overload current limiting protection.