Flow meter is one of the major types of process automation instruments and devices. Electromagnetic flow meter is widely used in metallurgy, electric power, coal, chemical industry, petroleum, transportation, construction, textile, food, medicine, agriculture, environmental protection and people's daily life In various fields of the national economy, it is an important tool for developing industrial and agricultural production, saving energy, improving product quality, and improving economic efficiency and management level. It occupies an important position in the national economy.