Abstract: The paper discribes the analysis of the Gamma-ray pulse-height spectraresulting from NaI detector using weighted least square iteration. The computerprogram has the function of searching for Gamma-ray peak automatically. It canbe used in the analysis of continuous, discrete or their superposition spectraBesides there are some function of the spectrum smooth, the correction of theshift in gain and zero energy channel intercept. Some results of the computerprogram are presented.