Disclosed are an ONU migration detection method, OLT, ONU and storage medium. The ONU migration detection method may include: receiving first identification information from an ONU, the first identification information is configured to uniquely identify a historical position accessed by the ONU; acquiring second identification information according to a current position of the ONU, the second identification information is configured to uniquely identify the current position; and comparing the first identification information with the second identification information, and determining that ONU migration occurs in response to the first identification information being mismatched with the second identification information.