The invention relates to a monitoring device beneficial to optical cable line maintenance. The monitoring device comprises a frame body, a control unit and a power supply assembly. The power supply assembly is connected with the control unit. At least two optical time domain reflectometers are connected to the control unit. The power supply assembly comprises a solar cell panel assembly and electric energy collectors, wherein each electric energy collector is provided with a first interface and a second interface, and an alarm assembly is arranged on each electric energy collector. The monitoring device has the advantages that the electric energy generated by the solar cell panel assembly is collected through the electric energy collectors, power is supplied to the control unit through the first interfaces, power is supplied to the optical time domain reflectometers through the second interfaces, the connectivity power supply of the control unit and the optical time domain reflectometers is ensured, the work intensity caused by the existing power supply assembly replacement is lowered, it is ensured that the optical time domain reflectometers can normally work when voltages of power supplies arranged in the optical time domain reflectometers are low, the simultaneous access of the first interfaces and the second interfaces is avoided through the alarm assemblies, and the voltage supply stability is ensured.