Abstract: Using multiple reflected echoes caused by the difference impedance of the solid-liquid interface, an ultrasonic system for measuring characteristic acoustic impedance of liquids was developed. The characteristic acoustic impedance of four materials were measured, such as methanol, ethanol, water and glycerol. Results indicated that the larger the liquid’s characteristic acoustic impedance value, the more accurate the system. Also, the impedance of CaCl2 solution was measured. Results indicated that the impedance was in linear with the concentration of solution, and the measurement error was no more than 2.7 g/L. Because of no need of transparence of ultrasound in liquids, this measurement system could be used to measure the impedance and concentration of a high attenuation liquid out from containers or pipeline wall.