Abstract: At present, the dam piping location system has excellent performance in dam leakage detection, but it can´t measure water level depth. An underwater directional ranging positioning system based on acoustic transducer was developed to improve the accuracy. The STM32F4 TIM2 was configured , which square wave as excitation signal source. Then the signal through the conditioning circuit for voltage amplification and power amplification , which is driven the transmitter hydroacoustic transducer to send signals to the water. The transmitted signal has been transmitted over a certain distance, which is received by receiver transducer to compares its amplitude and to at values of peaks and to determine the peak values. Finally, according to the number of sampling points and the interval between the number of points to achieve the underwater directional ranging positioning of the dam piping instrument. Furthermore, the paper proposes an adaptive pulse algorithm to address the error of single pulse measurement at different distances. Field test results show that the error range of the developed system is less than 4%, which can be used for small reservoir dam piping location detection, providing a new method for dam piping location.