The high-energy ball milling of Ni-66.7 at% Si elemental powder mixtures was carried out using a FRITSCH Puluerisette-5 mill. XRD was used to identify the phase evolutions during high-energy ball milling. The XRD patterns showed that the intensities of nickel peaks and silicon peaks gradually decreased with milling time increased from 1 h to 10 h, simultaneously, the peaks of NiSi2 and NiSi appeared. With milling time further increased to 45 h, single phase of NiSi2 formed. New peaks were observed after 75 h milling, which were indexed as FeSi. This reveals that long time high-energy ball milling will induce Fe contamination and that Fe exhibits greater activity and reacts with NiSi2 forming FeSi and NiSi. Moreover, the peaks intensity of FeSi and NiSi increased with milling time increased from 75 h to 180 h. The phase evolutions of Ni-66.7at% Si during high energy ball milling were discussed.