By systematically analyzing the single particle level and the occupation probability near the Fermi surface，and the rule of nuclear particle number deviations with proton numbers for N=8，20，28，50，82，126 neutron chains within the relativistic mean-field model with BCS theory，we have discussed the stability of the shell structure for the traditional neutron magic in the whole range of nuclear spectrum from neutron line to proton line，and predicted that traditional neutron magic number effect shall possibly disappear only in light neutron-rich nuclei. Our results are also compared with the results of other recent reports.