Abstract According to the spectrum experiment data, XU Guang-Xian proposed a theoretical basis for orbital energy level of ground state multi-electron atom, including the approximate rule:n+0.7l formula for the electronic configuration of neutral ground state multi-electron atoms and n+0.4l formula for the electronic configuration of ground state multi-electron ions. This rule given in mathematical expressions was very easy to be derived and solved the problem that the electronic configuration was difficult to be written correctly. The discussion and application of the two formulas could deepen the understanding of structure principles of electronic configuration and inherit research results of Chinese scientists.
