Gamma-ray spectrum analysis was essential for radioactive environmental monitoring, and it had been widely used in many areas of nuclear engineering. However, for the low-energy region of gamma-ray spectrum, weak peaks were contained in the fast-decreasing background, so it was difficult to extract characteristic information from original spectra. In order to get a better analytic result based on wavelet methods in frequency domain, we had processed the gamma-ray spectrometer data of Chang’E-1 and well extracted some useful information of spectral characteristic peaks. Then, we preliminarily mapped the distribution of net peak counts for potassium on lunar surface, which indirectly reflected the distribution of elemental abundance. At last, we compared our analytic result with that of Apollo and Lunar Prospector and found some consistencies and differences.