The non-invasive nature of ultrasonic flow-meters is prominent among many flow-meters．It does not need to destroy the internal structure of the pipe to know the liquid condition inside the pipe．The ultrasonic “V-shaped”time difference method is used to measure the condition of the liquid inside the pipeline，and the multiple pulse method is used to achieve the demand of high precision．The 52 single-chip microcomputer is used to carry out micro control and calculation，and the relevant results are displayed by LCD display screen． The device can be used to measure the liquid flow rate and flow direction change in non-transparent pipes．