The present invention relates to a filter assembly for a medical image signal and a dynamic decimation method using the same. The filter assembly includes a decimation filter that includes an integer number of multiplier accumulators (MACs), changes a cut-off frequency depending on a bandwidth of the medical image signal received through a dynamic impulse response update, and performs a decimation with respect to the received signal according to a decimation ratio, wherein the decimation filter determines a filter coefficient corresponding to an integer interval so as to up-sample the received medical image signal and supplies the filter coefficient to the MACs.