The present disclosure provides a method and a device for amplifying uplink light of a passive optical network, and a computer-readable storage medium. The passive optical network includes an optical network unit, an optical line terminal, and an optical amplifier provided between the optical network unit and the optical line terminal, and the method include: receiving a registration signal transmitted from the optical line terminal; determining a gain value of the optical amplifier, and performing gain value adjustment on the optical amplifier according to the determined gain value; and completing registration when an uplink optical signal transmitted to the optical line terminal through the optical amplifier reaches preset power.