The invention discloses an ultrasonic detection method for a frozen wall expansion speed. The method comprises the steps of modifying a freezer structure; accepting a sound ranging hole before ultrasonic detection; performing ultrasonic detection on the frozen wall expansion speed to obtain the frozen wall expansion speed; and then comparing the frozen wall expansion speed with the frozen wall expansion speed speculated by a temperature detection hole to monitor a frozen wall expansion process. With the ultrasonic detection method for the frozen wall expansion speed disclosed by the invention,early forecasting before freezing can be implemented, when the ultrasonic wave velocity is abnormal, the transit time is inconsistent with other detection results at the same level, the geological reason needs to be analyzed in time, the reasons such as a void and a groundwater flow rate are checked to achieve the purpose of early forecasting; in the freezing phase, when the frozen wall expansionspeed speculated by the ultrasonic wave changes suddenly, the abnormal condition of the frozen wall needs to be judged in time; freezing holes at the vicinity of the sound ranging area are checked one by one by use of the ultrasonic method or the longitudinal temperature measurement method in the freezer; and measures such as grouting and strengthening freezing are adopted in time for the freezing holes which are not closed to achieve the purpose of process monitoring and effect evaluation.