Abstract: In order to make a more in-depth theoretical study on the acoustic waves in the experiments of sound velocity measurement, sound velocity measurement methods and experimental principles are discussed.On the speed of sound analyzer transmitter and the receiver wave superposition between the incident wave and reflected the synthesis wave equation is deduced.The ultrasonic state between the two transducers is traveling wave and standing wave.The results show that the phase comparison method and the ultrasonic standing wave resonance method are used to measure the speed of sound.The relative errors between the measured results of the two methods and the theoretical value respectively are 2% and 1%.