Embodiments of the present invention provide a method for compatibility with a VDSL2 legacy customer premises equipment, including: selecting tones in preset locations from tones of a legacy line as training tones; controlling the training tones not to transmit data and modulating a pilot sequence on the training tones; calculating and feeding back clipped errors on a Vectored line; and calculating coefficients, for the training tones, of crosstalk of the legacy line in the Vectored line according to the pilot sequence and the clipped errors. The embodiments of the present invention further provide an apparatus and a system for compatibility with a VDSL2 legacy customer premises equipment.