The invention provides a preservative composition of blood DNA. The preservative composition of blood DNA comprises, by weight, 20 to 50 parts of a preservative, 5 to 15 parts of an anticoagulant, 0.5 to 5 parts of a nuclease inhibitor, 1 to 5 parts of a metabolic inhibitor and 40 to 70 parts of water, wherein the nuclease inhibitor comprises one or more of diatomite, bentonite, ethyl alcohol, formamide, vanadyl-ribonucleoside complex, dithioerythritol, diethyl pyrocarbonate, proteinase-K, heparin, beta-mercaptoethanol, hydroxylamine-O-copper ions, ammonium sulfate, dithiothreitol, cysteine, and 4-formylbenzoic acid and oxovanadium Schiff base complex.