The invention relates to a purification agent and a preparation method of the purification agent, mainly solving the problems of high bulk density, low utilization rate and high industrial application cost of the purification agent in the prior art. The purification agent comprises the following components in percentage by weight: (a) 20-95% of Cu-Zn-Al ternary hydrotalcite; and (b) 5-8% of an adhesive, wherein a hydrotalcite compound is ternary hydrotalcite which comprises bivalent ions Zn<2+> and Cu<2+> and trivalent ions Al<3+>; the molecular structure of the hydrotalcite compound is as follows: [CuyZn (1-x-y)Alx(OH)2](CO3)x/2.mH2O), wherein x represents the mole ratio of Al/(Zn+Cu+Al) and is 0.2-0.33; the mole ratio of Cu to Zn is 0.1-2; m represents the number of crystal waters and is 2-4. The purification agent can be used for purifying natural gas, synthesis gas and light gas-liquid hydrocarbon.