An optical fiber detection method, wherein the online optical fiber detection method comprises following steps: selecting by a network element management system an optical fiber path required to be detected and setting relevant parameters of an optical fiber detection device related to the optical fiber path, wherein the relevant parameters include: a wavelength, a pulse width, a measurement distance and acquisition time of detection light of an Optical Time Domain Reflectometer, OTDR, and optical fiber parameters; sending by the network element management system a detection starting instruction to the optical fiber detection device for the optical fiber detection device to detect the optical fiber path according to the detection starting instruction, and the optical fiber detection device emitting detection light towards the selected optical fiber path after receiving the instruction; controlling by the network element management system the optical fiber detection device to collect returned reflected light and analyse the collected reflected light to acquire intensity and reception time of the detection light and the reflected light; calculating a length 1 and an optical fiber loss coefficient α of the detected optical fiber according to formulas: 1=(1/2) ∗ (c/n) ∗ t and Ps = P0 ∗ e -2α1, wherein c represents a speed of light, n represents a refractive index of a medium and t represents the time elapsing from a moment the detection light is started to be emitted to a moment the reflected light is received, and comparing the intensity of the detection light and the intensity of the reflected light and the length 1 and the optical fiber loss coefficient α of the detected optical fiber to acquire a working status of the optical fiber path. selecting by a network element management system an optical fiber path required to be detected and setting relevant parameters of an optical fiber detection device related to the optical fiber path, wherein the relevant parameters include: a wavelength, a pulse width, a measurement distance and acquisition time of detection light of an Optical Time Domain Reflectometer, OTDR, and optical fiber parameters; sending by the network element management system a detection starting instruction to the optical fiber detection device for the optical fiber detection device to detect the optical fiber path according to the detection starting instruction, and the optical fiber detection device emitting detection light towards the selected optical fiber path after receiving the instruction; controlling by the network element management system the optical fiber detection device to collect returned reflected light and analyse the collected reflected light to acquire intensity and reception time of the detection light and the reflected light; calculating a length 1 and an optical fiber loss coefficient α of the detected optical fiber according to formulas: 1=(1/2) ∗ (c/n) ∗ t and Ps = P0 ∗ e -2α1, wherein c represents a speed of light, n represents a refractive index of a medium and t represents the time elapsing from a moment the detection light is started to be emitted to a moment the reflected light is received, and comparing the intensity of the detection light and the intensity of the reflected light and the length 1 and the optical fiber loss coefficient α of the detected optical fiber to acquire a working status of the optical fiber path.