A wavelength selective switch, comprising: a dual-microring resonator, comprising a first microring and a second microring that are connected in series, wherein the first microring and the second microring are silicon-based microring waveguides and respectively comprise one annular PN junction, and a direction of the annular PN junction of the first microring is the same as that of the annular PN junction of the second microring; an electric tuning module, wherein a first electric port of the electric tuning module is connected to a P zone of the first microring and an N zone of the second microring, a second electric port of the electric tuning module is connected to an N zone of the first microring and a P zone of the second microring, and the electric tuning module is configured to apply bias voltages with reverse directions to the annular PN junction of the first microring and the annular PN junction of the second microring; and a thermal tuning module, configured to adjust an operating temperature of the dual-microring resonator; characterized in that the electric tuning module is configured to apply the bias voltages with reverse directions to the annular PN junction of the first microring and the annular PN junction of the second microring, so that a refractive index of the first microring and that of the second microring reversely change, so that the dual-microring resonator is in a detuned state; the thermal tuning module is configured to adjust the operating temperature of the dual-microring resonator to change a resonant wavelength of the dual-microring resonator; and the electric tuning module is further configured to stop applying the bias voltages with reverse directions to the annular PN junction of the first microring and the annular PN junction of the second microring, so that the dual-microring resonator is in a resonant state at a changed resonant wavelength. a dual-microring resonator, comprising a first microring and a second microring that are connected in series, wherein the first microring and the second microring are silicon-based microring waveguides and respectively comprise one annular PN junction, and a direction of the annular PN junction of the first microring is the same as that of the annular PN junction of the second microring; an electric tuning module, wherein a first electric port of the electric tuning module is connected to a P zone of the first microring and an N zone of the second microring, a second electric port of the electric tuning module is connected to an N zone of the first microring and a P zone of the second microring, and the electric tuning module is configured to apply bias voltages with reverse directions to the annular PN junction of the first microring and the annular PN junction of the second microring; and a thermal tuning module, configured to adjust an operating temperature of the dual-microring resonator; characterized in that the electric tuning module is configured to apply the bias voltages with reverse directions to the annular PN junction of the first microring and the annular PN junction of the second microring, so that a refractive index of the first microring and that of the second microring reversely change, so that the dual-microring resonator is in a detuned state; the thermal tuning module is configured to adjust the operating temperature of the dual-microring resonator to change a resonant wavelength of the dual-microring resonator; and the electric tuning module is further configured to stop applying the bias voltages with reverse directions to the annular PN junction of the first microring and the annular PN junction of the second microring, so that the dual-microring resonator is in a resonant state at a changed resonant wavelength.