The invention discloses an optical fiber type field soil organic matter content fast detector, comprising an optical path module and a control module connected with the optical path module, wherein the optical path module comprises a photoelectric detector, an optical fiber, a probe, a near-infrared light emitting diode and a drive circuit, the optical fiber comprises a light input end, a reflected light measurement end and a soil detection end, the light input end is connected with the photoelectric detector, the reflected light measurement end is connected with the photoelectric detector, the soil detection end is connected with the probe, the control module comprises a signal amplification unit, a A / D conversion unit, a control unit, a display unit and a memory unit, the signal amplification unit is connected with the photoelectric diode and the A / D conversion unit, the control unit is connected with the A / D conversion unit, the display unit and the memory unit. The invention has the advantages that the optical fiber type field soil organic matter content fast detector avoids the natural limits such as weather, is portable, and can real-timely, quickly and accurately measure soil organic matter content and quickly store mass data.