A method for encoding a multi-channel signal and an encoder, where the encoding method includes obtaining a multi-channel signal of a current frame, determining an initial inter-channel time difference (ITD) value of the current frame, controlling, based on characteristic information of the multi-channel signal, a quantity of target frames that are allowed to appear continuously, where the characteristic information includes at least one of a signal-to-noise ratio of the multi-channel signal or a peak feature of cross correlation coefficients of the multi-channel signal, and an ITD value of a previous frame of the target frame is reused as an ITD value of the target frame, determining an ITD value of the current frame based on the initial ITD value and the quantity of target frames allowed to appear continuously, and encoding the multi-channel signal based on the ITD value of the current frame.