Abstract: Natural diamond (typeIa) photoconductive detectros (PCDs)are presented. The diamond elements have dimensions of 2mm × lmm × 0.7mm. Diamond PCDs have many unique characteristics, such as good stability, flat spectal response for 0.l~2.0keV X rays,low dark currents and insensitivity to visible andnear--UV light. Diamond PCDs are used to measure X rays on “Shenguang" facility. The sensitivity of PCDs is about 3 × 10^-4C/J at a bias voltage of 100v.