The present invention discloses a method for acquiring a PON port association relationship. An OLT where a standby PON port is located receives a protection packet from an optical network unit, parses the protection packet to obtain an identifier of an active PON port carried in the packet, and acquires an association relationship between the active PON port and the standby PON port according to an identifier of the standby PON port receiving the protection packet. When the present invention is implemented, the OLT where the standby PON port is located can acquire an association relationship between an active PON port and a standby PON port, and determine, according to the association relationship, whether the protection packet is valid or acquire, according to the association relationship, configuration information of the active PON port.