Abstract: A phased control-based noise cancellation method for through-casing acoustic logging was proposed to improve the low accuracy of measuring compressional wave velocity in formation in cases where poor bonding exists between the formation and casing. In this method, a phase control circuit was added to the signal conditioning module of the data acquisition circuit. It utilized adjacent receiver transducers to suppress casing waves and enhance formation wave signals by adjusting their phase relationship. By this way, signal phase delay and amplitude adjustment were achieved, so that adjacent transducers received casing waves with identical arrival time and amplitudes, which canceled each other out through superposition and thereby improving formation wave signal-to-noise ratio. To validate the effectiveness of this method, a phase shift circuit was designed, and experiments were conducted in a laboratory free-casing model well. The results show that this method effectively suppresses casing waves (with an amplitude reduction of 85%) and enables clear identification of compressional waves in formation, thus verifying its engineering feasibility.