The polynomial correction method is used to correct photon-counter position-sensitive detector′s distortion. The principle of these detectors is introduced and the causes of distortion are analyzed. Based on the theory of polynomial distortion correction, its correcting process in photon-counter position-sensitive detector has been proposed. According to this process, two photon-counting detectors based on a wedge-strip anode with different parameters are corrected, and the residual distortions are respectively 2.5 pixel and 1.2 pixel. The correction results show that polynomial distortion correction can be effectively applied to correction of photon-counter position-sensitive detector′s imaging distortion.