The study of a novel model for digital nuclear pulse signal Gaussian shaping based on amplitude factor and width factor is described in this paper. According to Sallen-Key filter(S-K filter in short), four formulae are established between the input and the output depending on Kirchhoff Current Law. With dual-factor parameter substitution, a general numerical recursive root is obtained by applying numerical differentiation algorithm. The correctness of the model is verified by computer simulation through the standard exponential decay signal and actual nuclear signal. The shaping factors are also confirmed. Finally, the digital Gaussian shaping technique is applied to the Energy Dispersive X-Ray Fluorescence system and, as a result, the spectrum of ⁵⁵Fe is obtained. Testing results show that digital shaping technique can improve the performance of the EDXRF system in such aspects as energy resolution and count ratio.