Based on the principle of ultrasonic echo ranging, uses precise time difference measurement technology to detect the distance between the Piezo sensor and the target, uses small angle, small blind area , has the advantages of accurate measurement, no contact, waterproof, anti-corrosion, low cost, etc. It can be applied to liquid level, Material level detection, unique liquid level, material level detection method. It can ensure that there are foam or large sloshing on the liquid surface and stable output is not easy to detect. The application industry includes liquid level, material level, material level detection, industrial process control and so on.