The neutron-rich even-even nuclei26–40Mg,28–46Si,30–48S,and32–56Ar are calculated with the RMF model and the phase-shift electron scattering method.Results show that level inversion of the 2s1/2and 1d3/2proton states may occur for the magnesium,silicon,sulphur,and argon isotopes with more neutrons away from the stability line.Calculations show that the variation of the central charge densities for30–48S,and32–56Ar are very sensitive to the 2s1/2and 1d3/2proton state level inversion,and the level inversion can lead to a large measurable central charge depletion to the charge density distributions for the neutron-rich isotopes.Calculations also show that the charge density diferences between the isotopes with and without central charge depletion can reveal not only the level inversion of the 2s1/2and 1d3/2proton states but also the behavior of the proton wave functions of both states.The results can provide references for the possible study of the nuclear level inversion and nuclear bubble phenomenon with electron scattering of short-lived nuclei at RIKEN or/and GSI in the future.In addition,direct nuclear reaction44S(n,d)43P or44S(3H,α)43P might also be a possible way to study the 2s1/2and 1d3/2proton state level inversion. The neutron-rich even-even nuclei 26-40Mg, 28-46Si, 30-48S, and32-56Ar are calculated with the RMF model and the phase-shift electron scattering method. Results show that level inversion of the 2s1 / 2 and 1d3 / 2 proton states may occur for the magnesium, silicon, sulfur, and argon isotopes with more neutrons away from the stability line. Calculations show that the variation of the central charge densities for 30-48S, and 32-56Ar are very sensitive to the 2s1 / 2 and 1d3 / 2proton state level inversion, and the level inversion can lead to a large measurable central charge depletion to the charge density distributions for the neutron-rich isotopes. Calculations also show that the charge density diferences between the isotopes with and without central charge depletion can reveal not only the level inversion of the 2s1 / 2 and 1d3 / 2 proton states but also the behavior of the proton wave functions of both states. the results can provide references for the possible study of the nuclear level inversion and nuclear nuclear phenomenon with electron scattering of short-lived nuclei at RIKEN or / and GSI in the future. In addition, direct nuclear reaction 44S (n, d) 43P or 44S (3H, α) 43P might also be a possible way to study the 2s1 / 2and 1d3 / 2proton state level inversion.