A method for estimating inter-channel delay and an apparatus for estimating inter-channel delay and an encoder are provided by the embodiments of the present invention. The method includes: obtaining signal sound field information from a cross-correlation function and a cumulative cross-correlation function of synthetic signals of left and right sound channels respectively; obtaining adjustment information of the cumulative cross-correlation function according to the sound field information that is respectively obtained; adjusting the cumulative cross-correlation function by using the adjustment information, so as to obtain the adjusted cumulative cross-correlation function; and determining a time corresponding to a maximum value in the adjusted cumulative cross-correlation function as an inter-channel delay. Therefore, the delay between the signals of the left and right sound channels can be estimated correctly, so as to improve the stability of the synthetic stereo sound field.