To the features of NaI(Tl) detector, we forth the Peak-seek method of symmetrical zero-area convolution. In order to improve the peak-seek ability of the low background, we have dealt with the data before peak filter. we will identify the nuclides by matching the nuclides Lib, confirm the borderline by first differential, calculate the activity by the net peak area, which would be subtracted of the background by logarithmic method. we get a formula fitting the energy-efficiency and product an application software that analyzing the energy spectrum gathered by ORTECT. As a result, it's best to ...