In this paper we report on the effect of rapid thermal annealing (RTA) on the characteristics of diffused crystalline p-n Si one-dimensional (1-D) position sensitive detector (PSD). The Si-PSDs are made with planer technology using thermal diffusion technique for Si doping. The lateral voltage produced by irradiation of He-Ne laser on PSD was parallel to the plane of junction and dependence linearly on laser spot position. The PSD that treated with best RTA condition (850 °C/15s) exhibited higher position sensitivity (104μV/mm) as compared with that for untreated PSD (31μV/mm). Furthermore, the best PSD gave a non-linearity error of 1.46%. The performance improvement factors such as uniformity, linearity, and responsivity of annealed Si-PSDs are presented and analyzed.