In order to obtain a neat gamma spectrum, two spectrometers were examined for the discrimination of the low-energy part of the 137 Cs gamma-ray spectrum which has electronic noise. Pulse shape discrimination (PSD) time measurement (timing) method was used for this purpose. This method, briefly, depends on the rise time measurement process of the signals.While implementing the process, a constant fraction discriminator (CFD) and a pulse shape analyzer (PSA) devices were used separately. Obtained spectra from the spectrometers were compared with each other. To perform an exact comparison, partial and complete discrimination processes were realized. After the comparison, it was concluded that the discrimination process through the spectrometer with PSA device was more successful than that of the other one. It was suggested that the PSD method using the PSA device would give a clearer gamma spectrum when accumulating it by a NaI(Tl) scintillation detector.