The antiferromagnetic coupling in Fe/Si multilayers was investigated with spa cers varying from pure Si to heavy-doped n-type and p-type Si. It was found that interlayer diffusion between Fe and Si occurred even though the multilayers sho wed well-defined layer structure, and the diffusion dominated the hea vy-doped Si, which made no difference at all for the antiferromagnetic coupl ing with different type of Si. Furthermore, the antiferromagnetic coupling in Fe/Si multi lay ers still goes on while the diffusion between Fe and Si layers enhanced and the layer structure was degraded to some extent after annealing.