Abstract: The WNW-trending Changping-Fengnan buried active fault on the southern margin of Yanshan Mountain is clearly identified on the Landsat images as a dark bandlike linear imagery several kilometers wide. This imagery was produced under a specific climatic condition due to the slight difference of loose sediment of watery zone and its adjacent area in density represented by reflective electromagnetic wave spectra on the imeges. And the watery zone was formed with the migration of ground water along the active fault and ascension on ground surface.By analyzing geological and geophysical data, it has been proposed that Changping-Fengnan buried active fault might be formed during the late Mesozoic time. This was a crustal fault, characteristic of dextral slip, that has dissected the Conrad and the Moho discontinuity since Quaternary.