Method, apparatus and system for initializing line

Provided is a method for initializing a line. Whether in an uplink direction or in a downlink direction, data information is not sent at a data symbol position in a corresponding direction before a coefficient matrix (a cancellation coefficient matrix and a precode coefficient matrix) is obtained; and a CO firstly acquires transmission channels on all lines in the uplink direction so as to eliminate crosstalk generated during data transmission in the uplink direction of all the lines; and in this way, it can ensure that there is no crosstalk in the uplink direction after a backward channel of an uplink error sample is established, a crosstalk channel in the downlink direction can be borne on a data symbol sent to the CO by a CPE, and the CO can calculate, according to crosstalk channel information in the downlink direction which is fed back by the CPE, a transmission channel in the downlink direction of the lines so as to obtain a downlink precode coefficient matrix to eliminate crosstalk in the downlink direction, thus having no influence on a service between the CO and the CPE, and reducing the influence caused by the adding of a new line on service data to the greatest extent.