Abstract: A wavelet thresholding function used to denoise radon γ energy spectra of low radioactivity method, was proposed in the paper. By analyzing field test results, three traditional denoising methods, multi-points smoothing, FFT and wavelet soft thresholding function were compared with the wavelet thresholding function. Analyzing results show that by using wavelet thresholding function γ energy spectra characteristics, such as peak ratio, peak counts, peak area and background are much clearer than those by using traditional denoising methods. At the mean time, this method can keep detail character of original signal.