The DC-bus cable of a large scale photovoltaic（PV） system with high voltage and long length is usually buried in soil

and its low-frequency electrical parameters hardly change when the cable’s outer protective layers are damaged

which has potential safety hazards leading to faults such as short-circuit

grounding and arc etc. Cables with damaged outer protective layers are difficult to be found using normal electrical detective methods. However

the high-frequency characteristic impedance will change with damage in cables.Consequently

a method based on spread spectrum time domain reflectometry（SSTDR） was proposed to detect damage problems of PV DC-bus cable. The variations of the high-frequency characteristic impedance of damaged PV DC cable were analyzed

thus the feasibilities of detecting the SSTDR-based damaged cable problems were evaluated. And a new location strategy based on SSTDR is also put forward to reduce the influence of external environment interference. The results of simulation and experiments both have proved the validity and efficiency of the SSTDR-based damage on-line detection and location of PV DC bus.