In this study, Ni germanide Schottky barrier diodes on n-Ge (100) substrate were fabricated by sputtering metal Ni on Ge, followed by annealing in N2 atmosphere from 300 to 500℃ in a fuace. The results of x-ray diffraction (XRD)show that the Ni germanide was formed and the diffraction line of (111) was observed in all samples. The structure of Ni germanide is orthorhombic with lattice parameters a=5.811, b=5.381, c=3.428. However, the lines (121) and (002) were observed only in the samples annealed at a temperature higher than 400℃. The influence of annealing temperature on the electrical properties of Ni germanide Schottky barrier diodes on n-Ge (100) substrate was investigated. Experimental results indicated that Schottky barrier diodes on n-Ge (100) with current-voltage (I-V) rectifier characteristics were obtained. The Ion/Ioff ratio of the Schottky diode obtained by using a 300℃ annealing process is the highest. The Schottky barrier heights were evaluated by the capacitance-voltage method.