An optical add/drop multiplexer, comprising: a first microring resonant cavity, coupled with a first side of a first waveguide in an optical network, and configured to receive, from the first waveguide, a first optical network signal whose wavelength is a first wavelength; a second microring resonant cavity, coupled with the first side of the first waveguide, and configured to receive the first optical network signal transmitted by the first microring resonant cavity, and transmit the first optical network signal to the first waveguide, wherein a transmission direction of the first optical network signal in the first waveguide is a first direction; and configured to receive, from the first waveguide, a second optical network signal whose wavelength is the first wavelength and whose transmission direction in the first waveguide is a second direction, wherein the first wavelength is a resonant wavelength of the first microring resonant cavity and the second microring resonant cavity, the second direction is a specified direction of a to-be-processed optical network signal transmitted in the first waveguide, and the second direction is opposite to the first direction; a first optical circulator, wherein a first end (a) of the first optical circulator is connected to one end of a second waveguide, and a second end (b) of the first optical circulator is connected to one end of a third waveguide; configured to transmit, to the second microring resonant cavity, the first optical network signal transmitted by the first microring resonant cavity, and to receive the second optical network signal transmitted by the second microring resonant cavity; wherein the other end of the second waveguide is coupled with the first microring resonant cavity; and the other end of the third waveguide is coupled with the second microring resonant cavity; and a second optical circulator, wherein a third end (f) of the second optical circulator is connected to a third end (c) of the first optical circulator by using a fourth waveguide, and a first end (d) of the second optical circulator is connected to one end of a fifth waveguide; configured to receive the second optical network signal transmitted by the first optical circulator, and extract and distribute, by using the fifth waveguide, the second optical network signal to an optical network node on which the optical add/drop multiplexer is located. a first microring resonant cavity, coupled with a first side of a first waveguide in an optical network, and configured to receive, from the first waveguide, a first optical network signal whose wavelength is a first wavelength; a second microring resonant cavity, coupled with the first side of the first waveguide, and configured to receive the first optical network signal transmitted by the first microring resonant cavity, and transmit the first optical network signal to the first waveguide, wherein a transmission direction of the first optical network signal in the first waveguide is a first direction; and configured to receive, from the first waveguide, a second optical network signal whose wavelength is the first wavelength and whose transmission direction in the first waveguide is a second direction, wherein the first wavelength is a resonant wavelength of the first microring resonant cavity and the second microring resonant cavity, the second direction is a specified direction of a to-be-processed optical network signal transmitted in the first waveguide, and the second direction is opposite to the first direction; a first optical circulator, wherein a first end (a) of the first optical circulator is connected to one end of a second waveguide, and a second end (b) of the first optical circulator is connected to one end of a third waveguide; configured to transmit, to the second microring resonant cavity, the first optical network signal transmitted by the first microring resonant cavity, and to receive the second optical network signal transmitted by the second microring resonant cavity; wherein the other end of the second waveguide is coupled with the first microring resonant cavity; and the other end of the third waveguide is coupled with the second microring resonant cavity; and a second optical circulator, wherein a third end (f) of the second optical circulator is connected to a third end (c) of the first optical circulator by using a fourth waveguide, and a first end (d) of the second optical circulator is connected to one end of a fifth waveguide; configured to receive the second optical network signal transmitted by the first optical circulator, and extract and distribute, by using the fifth waveguide, the second optical network signal to an optical network node on which the optical add/drop multiplexer is located.