Abstract: Abstract: In order to study the response characteristics of ultrasonic acoustic signals in different freezing stages, a thermo-acoustic unidirectional coupling numerical simulation method was proposed by using COMSOL software solid heat transfer and pressure acoustic module. The temperature field evolution characteristics and the variation of ultrasonic acoustic parameters between the two freezing holes in different freezing stages were obtained. The results are as follow: (1) The reduction of 25 d,40 d and 42 d sound pressure are 51.83%,51.48% and 10.29% respectively than 90 d;(2) The peak sound pressure of the frozen wall intersection is 45.91% higher than the peak sound pressure of the uncrossed circle;(3) Ultrasonic average velocity are 2088 m/s, 2379 m/s, 2670 m/s and 2885 m/s respectively increase with freezing time（25 d、40 d、42 d、90d）.According to the on-site test results, the measured value of the field and the simulated value are within 5%, which prove this numerical simulation method can be an effective method to forecast acoustic parameters of freezing wall at different stages.