The invention relates to a chlorine-alkali wastewater treatment agent and a preparation method thereof. The chlorine-alkali wastewater treatment agent comprises the following raw materials in parts by weight: 25-30 parts of sodium silicate, 68-76 parts of limestone, 20-22 parts of polyacrylamide, 13-18 parts of sodium hypochlorite, 20-27 parts of Chinese roses, 35-39 parts of roses, 20-28 parts of cocoanut shells, and 33-39 parts of peanut shells. The chlorine-alkali wastewater treatment agent provided by the invention can oxidize and catalyze the impurities in wastewater, effectively remove the impurities in wastewater, and discharge the impurities after the impurities are treated and the standard is met, and the treated wastewater meets the national primary discharge standard. The chlorine-alkali wastewater treatment agent prepared by the method has the following advantages: the raw materials are easily accessible, the cost is low, the process is simple, the operation is simple and convenient, and the agent has good environmental benefits and economical benefits. For the wastewater treated by the wastewater treatment agent, the removal rate of the COD in wastewater is effectively increased to 21.8%, and the effect is remarkable.