The invention relates to an in-situ nano TiC particle reinforced Al-Si based composite material and a preparation method thereof. The mass percentage of nano TiC particles in the composite material isgreater than 0.05% and less than or equal to 5.0%, and a matrix is an Al-Si alloy; nano TiC particles are formed in situ by a chemical reaction of Al powder, Ti powder and carbon nanotube powder, andthen are added to an Al-Si alloy melt in the form of an intermediate alloy; and the Al-Si alloy of the matrix comprises the following components in percentage by mass: 6.5-7.5% of Si, 0.25-0.45% of Mg, and the balance Al. The composite material prepared by the preparation method has excellent properties of high strength, high toughness, high wear resistance and the like.