The T3 series ultrasonic watermeter is a new generation of smart water meter designed for agricultural irrigation and water resource monitoring. It is an all-plastic smart water meter with nylon as the main material. It is installed in the pipe by clamping the meter body which is only 50 mm in thickness between the two flanges of the pipe. The new generation of ultrasonic water meter uses a technology similar to that of ultrasonic flowmeter. The transit time difference is obtained through correlation calculation of captured signal waveform, thus featuring high precision, low drift, anti-interference, stability and reliability. The smart water meter also uses a signal acquisition hardware with a dynamic range of 30dB, so it can resist medium scaling inside the pipe and is suitable for measurement of muddy water with sediments. Technology applied: single channel ultrasonic principle, waveform analysis, correlation calculation, signal amplitude adaptive.