The present disclosure provides example channel parameter estimation methods and related apparatuses. In one example method, a cable modem (CM) obtains a second data frame through a downlink channel between the CM and a cable modem termination system (CMTS). The second data frame is generated after a first data frame sent by the CMTS is modulated through the downlink channel, a zero-bit-loaded symbol of the first data frame includes no valid codeword, but includes a zero-bit-loaded NCP and an idle codeword identified by the zero-bit-loaded NCP, and the idle codeword includes a data sequence used for channel parameter estimation. The CM can estimate a channel parameter of the downlink channel based on a data sequence in an obtained zero-bit-loaded symbol of the second data frame and the data sequence in the zero-bit-loaded symbol of the first data frame.