A communication device is disclosed. The communication device includes a transceiver circuit, an echo canceler, and a processor. The transceiver circuit is configured to transmit a test signal to a channel. The echo canceler is configured to obtain a plurality of echo power of a reflected signal corresponding to the test signal. The processor is configured to obtain a plurality of positions on the channel according to a parameter value. The parameter value is N, a number of the plurality of positions is N, and the plurality of positions corresponds to the top N largest of the plurality of echo power. The echo canceler is further configured to eliminate part of the plurality of echo power corresponding to the plurality of positions according to the plurality of positions.