The invention discloses an adaptive echo cancellation method comprising the steps of estimating an echo signal y(k) by an adaptive filter according to a reference signal x(k) of a sound emitting unit; computing a residual signal e(k) according to y(k) and a signal d(k) collected by a microphone; computing a power spectrum xPow(f) of a frequency domain reference signal X(f); computing a power spectrum ePow(f) of a frequency domain residual signal E(f); computing a related power spectrum xePow(f) of a conjugate residual signal E*(f) of E(f) and X(f); computing a related coefficient cohxe(f) of X(f) and E*(f); and using cohxe(f) as an adaptive step length factor of the adaptive filter to update an adaptive filter coefficient. According to the technical scheme of the method provided by the invention, the related coefficient between the residual signal and the reference signal is used as the adaptive step length factor, and thus effective echo cancellation can be performed on each voice state.