We investigate the nuclear shadowing effect on the K factor in the Drell-Yan process by introducing a shadowing factor into the corresponding quantum chromodynamical αs order corrections. K factors for Au-Au collisions are calculated at the centre-of-mass system energies √s = 60, 130 and 200 GeV while the nuclear shadowing factor is taken into account. The numerical results indicate that the nuclear shadowing factor obviously raises the K value in the small x region, and for the same nucleon the K value becomes smaller as the energy increases. The nuclear shadowing effect could be one reason for creating the non-constancy of the K factor.