The problem of noise in power transformer was pay attention to by this paper. The paper presents the design methodology for the active noise control (ANC) of sound disturbances in power transformer. The active noise attenuation algorithm uses the framework of output-error based optimization of a linearly parameterized filter for feedforward sound compensation to select optimal location of sensor and demonstrate the effectiveness of active noise attention in a large power transformer. The ANC controller can automatically measure the sound disturbances and select the compensate parameters to realize the noise cancellation. With 220kV power transformer noise cancellation, for example, the simulating results prove that the ANC technology to cancel the noise in power transformer is an effective way.