Various processes of the Mo/Si thin films deposited on Si (001) substrates by RF magnetron sputtering technique were carefully investigated and the MoSi2 thin film with the single tetragonal phase and low resistivity was successfully prepared. X-ray diffraction, scanning electrical microscopy, atomic force microscope and Four-probe resistance meter were used to determine their structures, surface morphologies and electrical properties. Results show that the electrical property of the Mo/Si films depends strongly upon their microstructure and the phase composition. The as-deposited film mainly belongs to amorphous. After annealing at the high temperature. The great change of the film crystallization structure takes place, and its phase composition varies with the as-deposited processes. The effect of the crystallization enhances obviously, and the square resistance of the film drops greatly.