The invention discloses face-centred cubic structure Ti3Si nano particles and a preparation method thereof. In the method, titanium powder and silicon powder are used as main materials, argon is used as protective gas, alcohol is used as liquid medium for ball milling, a planetary high-energy ball mill and a vibration drier are used as main production devices, and a mechanical alloying method is used to prepare the face-centred cubic structure Ti3Si nano particles. The method has the advantages of simple technology, easily-controlled parameters, short production cycle, low energy consumption and no environment pollution, and is fit for industrialization production. The face-centred cubic structure Ti3Si nano particle has the advantages of small diameter of 15-120nm, low density, high strength, high temperature resistance, oxidation resistance, good electrical conductivity and heat conduction, and the like, and has wide application prospect and huge potential economic benefits in engineering technology, space technology, national defense industry, micro-electronics and other fields.