Abstract: Based on the physical model and the calculating method developed by the authors, the calculation software of the spatial distribution of density of x-ray photons in solid is made. The scattering of electron beam with energy in KeV in solid and the excitement of x-ray photons can be simulated by using this program. The quantitative results-of the distributionof density of x-ray photons and the spatial range including various proportion of the photons are also obtained. It is significant for quantitative research of electron microscopy.