A corrosion-resistant magnetostrictive level gauge for water conservancy hoists uses a sealed probe and a magnetic float to measure water level accurately in damp, splash-prone, and mildly corrosive areas. The probe contains a magnetostrictive waveguide wire. A permanent magnet is built into the float, which moves with the water surface. The transmitter sends a short current pulse down the waveguide. At the float position, the pulse magnetic field interacts with the float magnet and generates a torsional strain wave in the wire. This wave travels back to a pickup coil in the gauge head and becomes an electrical signal. The electronics measure the time between pulse emission and wave reception. Because the wave speed is stable, the gauge calculates the distance from the head to the float and converts it into liquid level. Corrosion resistance comes from a 316L stainless steel probe tube, PTFE or PFA coating, an IP68 sealed housing, and corrosion-resistant cable glands. The non-contact float and smooth probe reduce scaling, wear, and blockage. Common outputs include 4-20 mA, HART, RS485/Modbus, and relay alarms for hoist control and monitoring systems. Regular cleaning and zero/span checks help maintain long-term accuracy. This design provides stable measurement, low maintenance, and reliable operation in water conservancy hoist applications. The gauge can be installed vertically in sumps or tanks, with the probe fully immersed, and its local display and remote signal support safe hoist operation and early corrosion monitoring.