The invention provides a noise treatment system for the boundary of a transformer noise-reduction sound barrier. The noise treatment system comprises a secondary sound source (1), a reference sensor (2), an error sensor (3), a controller (4) and the noise-reduction sound barrier (5); the reference sensor (2) and the error sensor (3) are connected with the controller (4), and the controller (4) isconnected with the secondary sound source (1); the sound barrier (5) is arranged around a transformer, the secondary sound source (1) is fixed to the upper portion of the sound barrier (5), the soundbarrier (5) hinders linear propagation of transformer noise, the reference sensor (2) collects diffraction noise, and the error sensor (3) collects a noise signal of a noise elimination area; the controller (4) receives data of the reference sensor (2) and the error sensor (3) and processes the data, a processed noise reduction signal is sent to the secondary sound source (1), and the secondary sound source (1) plays noise-reduction sound, the noise-reduction sound and the diffraction noise are mutually superimposed, and thus active noise reduction is achieved.