An optical network unit authentication method, an optical line terminal and an optical network unit, which do not allow an ONU to be illegally migrated to and be used in OLTs of the other operators, so as to realize the connection between the ONU and an operator. The embodiments of the present invention comprise: when an optical network unit (ONU) is on-line, an optical line terminal (OLT) acquires first operator information about the ONU, wherein the first operator information is operator information about an operator to which the ONU belongs; the OLT compares the first operator information with second operator information, wherein the second operator information is operator information about an operator to which the OLT belongs; and if a comparison result indicates that the OLT and the ONU belong to different operators, the OLT determines that the ONU authentication fails.
