The invention provides cold work die steel. The cold work die steel comprises C, Si, Mn, Cr, Mo, W, V, P, S, Cu, Mg, Ti, Sr, Zr, B, Zn, Re, Sn, Pb, Be, Sc, Li, Ni, La, Al and the balance iron, wherein the sum of the mass percentages of the components is 100%. The nodular cast iron comprises multiple kinds of nonmetal, metal and transition metal elements. Because the elements are added and cooperate with one another, the oxidation resistance, the corrosion resistance, the abrasion resistance, the compression resistance and the shock resistance of a compressor cylinder block of an air conditioner are improved, and the service life of the compressor cylinder block of the air conditioner under severe working conditions is prolonged.