An active noise control system and associated auto-selection method for modeling a secondary path for the active noise control system are provided. The method includes the steps of: receiving a reference signal; filtering the reference signal with a secondary-path estimation filter to obtain a filtered reference signal, wherein the secondary path estimation filter is determined from a plurality of candidate secondary-path estimation filters; filtering the reference signal with an adaptive filter to provide a compensation signal; sensing a residual noise signal at a listening position of the active noise control system; and adapting filter coefficients of the adaptive filter according to the residual noise signal and the filtered reference signal.