Semi-active WDM wavelength division protection system

The invention discloses a semi-active WDM wavelength division protection system which comprises a backlight connector, an analog-to-digital converter, a pre-amplifier, an FD optical probe, an MCU control processing center, an optical switch, an optical splitter and mini wavelength division multiplexing and demultiplexing, the backlight connector is in line connection with the MCU control processing center, and the MCU control processing center is in line connection with the optical switch and the analog-to-digital converter. According to the semi-active WDM wavelength division protection system, light intensity can be detected when an optical fiber line passes through the optical fiber splitter and is split by 3% to be connected into the FD optical probe, the light intensity is input intothe analog-digital converter through the pre-amplifier, the optical power of the optical fiber line is calculated through the MCU control processing center, the optical power real-time monitoring function is achieved, and the