The invention relates to a silicon carbide particle reinforced 316L stainless steel substrate composite material and a preparation method thereof. The silicon carbide reinforced 316L stainless steel substrate composite material comprises a 316L stainless steel substrate and silicon carbide particles evenly distributed in the 316L stainless steel substrate. The volume fraction of the silicon carbide particles is 2-30%. According to the preparation method of the silicon carbide particle reinforced 316L stainless steel substrate composite material, raw material powder is prepared into slurry and ball-milling is conducted by using a KD-1 polyester polyamine compound dispersant, so that the silicon carbide particles and the metal powder are fully mixed, agglomeration is avoided, therefore the powder which is subjected to ball-milling has a larger specific surface area, and later sintering densification is facilitated; and hot-pressing sintering is conducted so that the silicon carbide particle reinforced stainless steel substrate composite material with the high density and strength can be obtained. The preparation method of the silicon carbide particle reinforced 316L stainless steel substrate composite material is simple in process and short in preparation period, the material is high in density and strength.