The invention provides an optical fiber defect detecting method and device. The optical fiber defect detecting device comprises a data processor, a pulse laser, a time data converter and an optical detector, wherein the pulse laser is used for emitting a laser pulse signal to a to-be-detected optical fiber under the control of the data processor; the optical detector is used for detecting whether the to-be-detected optical fiber generates a reflected light signal in the laser pulse signal transmission process and sends a trigger signal to the time data converter when detecting the reflected light signal; the time data converter is used for recording first time the pulse laser spent emitting the laser pulse signal and second time the pulse laser spent receiving the trigger signal and sends the first time and the second time to the data processor; the data processor is used for calculating positions of defects of the to-be-detected optical fiber according to the time difference between the first time and the second time as well as the light propagation speed. With the adoption of the optical fiber defect detecting method and device, the defects of the optical fiber can be detected conveniently and rapidly.