We have developed a one-dimensional position-sensitive detector (1-D PSD) for X-ray backscatter imaging which had a scintillator–fiber- position-sensitive photomultiplier (PSPMT) structure. Scintillators of the detector were covered by diffused reflection material. Teflon and the fiber of the detector was covered by mirror reflection material an aluminum foil. The detector was composed of a 1×25 LYSO array which was coupled with 25 plastic fibers. Another end of these fibers was twisted into a 5×5 array and coupled with a PSPMT R8520. The detector element's area was 4.2×20 mm 2 and the position resolution was 4.2 mm. We tested the positioning histogram of the detector set up an X-ray backscatter imaging system, and obtained an X-ray backscatter image from it.