The present disclosure provides an optical isolator which includes a planar lightwave circuit, a magneto-optic thin film and a metal thin film with a magnetic field. A channel for transmitting an optical signal is configured in the planar lightwave circuit. The magneto-optic thin film is disposed on the planar lightwave circuit, and a plane on which the magneto-optic thin film is located is parallel to the channel. The metal thin film is disposed on the magneto-optic thin film.