The invention discloses a power supply for an ultrasonic phased array well wall imaging system. The power supply comprises a voltage pre-stabilizing assembly and a linear voltage stabilizing assembly which are connected, wherein the voltage pre-stabilizing assembly comprises a voltage pre-stabilizing module, a filter and a first shielding case; the input end of the voltage pre-stabilizing module is used for being connected with a power supply source; the input end of the filter is connected with the output end of the voltage pre-stabilizing module; the voltage pre-stabilizing module and the filter are located in the first shielding case; the linear voltage stabilizing assembly comprises a series-connection type voltage stabilizing circuit, a capacitor and a second shielding case; the input end of the series-connection type voltage stabilizing circuit is connected with the output end of the filter; the capacitor is connected between a base of a triode of the series-connection type voltage stabilizing circuit and the ground end of the filter; the series-connection type voltage stabilizing circuit and the capacitor are located in the second shielding case. According to the power supply for the ultrasonic phased array well wall imaging system, ripple noise generated during use of the power supply is low and cannot obviously influence ultrasonic echo signals, and the power supply can be applied to the ultrasonic phased array well wall imaging system better.