An apparatus and method for monitoring optical fiber obstructions in an optical split network is described. The monitoring apparatus comprises a broadband-monitoring light source module, an optical circulator, an optical spectral analyzer, a high-density multi-wavelength OTDR, a controlling computer, a wavelength division multiplexer, a specific wavelength optical filter, a monitoring-waveband reflector, and an optical channel selector. The monitoring apparatus utilizes the specific wavelength optical filter and the monitoring-waveband reflector to collectively construct an optical split network optical fiber obstruction monitoring apparatus for the passive optical network having multiple split routes by filtering, reflecting, and transmitting coming lights, so as to achieve the purposes of locating the obstructed split routes and obstruction locations at the same time.