The invention relates to a geotechnical anchor or anchor cable length electrical pulse detection method and detection system. The detection method includes the following steps that: two anchor rods oranchor cables form an electrical signal transmission system, pulse signals are emitted into the two anchor rods or anchor cables at the exposed ends of the two anchor rods or anchor cables, and at the same time, pulse reflected signals are collected at the exposed ends of the two anchor rods or anchor cables; and the length of a shorter one of the two anchor rods or anchor cables is calculated according to a formula L1=V1deltat1/2, wherein v1 is the transmission speed of the electrical pulse signals in the anchor rods or anchor cables, and deltat1 is the time difference of the collection of the pulse reflected signals and the emission of the electrical pulse signals. With the geotechnical anchor or anchor cable length electrical pulse detection method and detection system of the inventionadopted, the problems of poor effect, low repeatability of detection results and unsuitability for the detection of long anchor rods or anchor cables of existing anchor or anchor cable length detection methods can be solved, and requirements of project acceptance inspection can be satisfied.