Where 𝑸 is the momentum transfer vector or the so-called wave vector, 𝑭(𝑸) is the reduced structure function, 𝑸 𝒎𝒂𝒙 and 𝑸 𝒎𝒊𝒏 are the maximum and minimum limitations of momentum transfer vector in the diffraction experiment, respectively. The 𝑭(𝑸) can be obtained by making structure function 𝑺(𝑸) independent to the wave vector in order to amplify the signal at high 𝑸 range. The advantages of using rPDF is that it can be directly derived from the scattering data which make random uncertainties constant, while getting PDF 𝒈(𝒓) also needs an assumption of the value of the average number density, which is hard to obtain accurately by experiment. In addition to the atom-atom distance, both PDF and rPDF can provide information about structural features, including coordination number, average atom density, and atomic periodicity. During the last decades, PDF analysis was mainly based on X-ray and neutron scattering and became a well-established technique for the structural characterization of crystalline and amorphous materials. As for X-ray PDF and neutron PDF, electron-PDF was obtained by applying Fourier transformation to structure function-𝑺(𝑸). Such a structure function can easily be extracted from electron diffraction patterns. Here, by utilizing the advantages of the high spatial resolution and tuneable illumination area given by TEM, the PDF profile could be obtained at micronscale to small nano-scale.