The Fe/X (X = C, Si, Ge) films were deposited on glass substrates by magnetron sputtering, and then they were annealed in vacuum. Their magnetic and transport properties are compared. For Fe/C films, the annealing process gives rise to the enhancement of saturation magnetization, the increase of the Fe particle size, and the reduction of the magnetoresistance (MR). For Fe/Si films, the annealing process causes the appearance of the Fe particles and the enhancement of MR. For Fe/Ge films, no Fe particles can be formed in the films. The unsaturated MR was observed in the as-deposited Fe/Ge film. Thus, the microstructures, magnetism, and transport properties can be tuned by the group-IV elements and the postannealing process. This paper may be beneficial to the group-IV-based spintronics.