Passive optical network monitoring device and monitoring method thereof

The present invention discloses a passive optical network monitoring device and monitoring method thereof, in which a wavelength division multiplexer is disposed between the optical signal source and a plurality of optical paths to correspondingly transmit multiple optical signals; in addition, an optical switch is corresponded to the optical paths of the wavelength division multiplexer to selectively switch and connect to at least one of the optical paths; an optical time domain reflectometer is electrically connected to the optical switch to generate an optical detection signal to the optical switch, making it select at least one of the optical paths for transmitting the optical detection signal. Therefore, using the operations of the optical time domain reflectometer and the optical switch, monitoring and detection can be directly performed at the final zone of the beam splitter, thereby effectively monitoring each optical fiber in the passive optical network, while providing effectiveness of lower price a