It is shown that the 3d⁵(⁴X)4s(⁵X) of 4s satellites, except to the coupling between 3d⁵4s(^7.5S)and 3p→3d transition, plays a key role on the magnitude of photoionization of 4s cross section. The coupledequation method is improved to calculate this resonance by including these channels. The results of calculationsare compared with the experimental data from 46 eV to 56 eV photon energies, which are in gcxxt agreementwith the experiment.