A detection device for high-dynamic-range optical time domain reflection, comprising a Raman laser, an OTDR detection laser, a wavelength division multiplexer WDM, a control module, a light receiving and optical signal processing module, and a circulator, wherein the Raman laser and the OTDR detection laser are respectively connected with the WDM, a light outlet of which is connected with a light inlet of the circulator, and Raman pulse laser emitted by the Raman laser and pulse light emitted by the OTDR detection laser are multiplexed by the WDM and then enter an optical fiber to be detected via an I/O optical port of the circulator; wherein the light receiving and optical signal processing module is connected with a light outlet of the circulator to obtain Rayleigh backscattered light and/or Fresnel reflected light returned from the optical fiber to be detected; wherein the light receiving and optical signal processing module is also connected with the control module to send related information of reflection light to the control module; wherein the control module is connected to a driving pin of the Raman laser to control the Raman laser to emit, according to the related information of reflection light, at least two optical pulses with a time interval within one detection time period, characterized in that the control module is used to control the Raman laser to send Raman pulse laser again to the optical fiber to be detected, if light intensity of the returned Rayleigh backscattered light and/or Fresnel reflection light detected in a preset time period within one detection period of the pulse light emitted by the OTDR detection laser is less than a preset threshold; and wherein when said one detection period of the pulse light emitted by the OTDR detection laser is specifically Nms, the preset time period is Mms after the OTDR detection laser emits the pulse light in a current detection period, where said Mms takes a value from an interval [0, N/2], M and N are corresponding time parameter values. wherein the Raman laser and the OTDR detection laser are respectively connected with the WDM, a light outlet of which is connected with a light inlet of the circulator, and Raman pulse laser emitted by the Raman laser and pulse light emitted by the OTDR detection laser are multiplexed by the WDM and then enter an optical fiber to be detected via an I/O optical port of the circulator; wherein the light receiving and optical signal processing module is connected with a light outlet of the circulator to obtain Rayleigh backscattered light and/or Fresnel reflected light returned from the optical fiber to be detected; wherein the light receiving and optical signal processing module is also connected with the control module to send related information of reflection light to the control module; wherein the control module is connected to a driving pin of the Raman laser to control the Raman laser to emit, according to the related information of reflection light, at least two optical pulses with a time interval within one detection time period, characterized in that the control module is used to control the Raman laser to send Raman pulse laser again to the optical fiber to be detected, if light intensity of the returned Rayleigh backscattered light and/or Fresnel reflection light detected in a preset time period within one detection period of the pulse light emitted by the OTDR detection laser is less than a preset threshold; and wherein when said one detection period of the pulse light emitted by the OTDR detection laser is specifically Nms, the preset time period is Mms after the OTDR detection laser emits the pulse light in a current detection period, where said Mms takes a value from an interval [0, N/2], M and N are corresponding time parameter values.