The invention relates to a composite heat stabilizer and a preparation method, belonging to the field of chemical agents. The composite heat stabilizer comprises a heat stabilizer, zinc stearate, hexadecanol, beta-diketone, PE (Polyethylene) wax, a composite oxidation inhibitor, phosphorous ester and mineral oil; and the reasonable chemical synthesis and the complex formulation are carried on the heat stabilizer, the zinc stearate, the hexadecanol, the beta-diketone, the PE (Polyethylene) wax, the composite oxidation inhibitor, the phosphorous ester and the mineral oil to obtain a finished product. The stabilizer relates to a mixture of disulphide group acetic acid iso-octyl dimethyl tin and organic acid rare earth; according to the preparation method, all the components are dissolved and compounded in thermal state to prepare the composite heat stabilizer, thereby reducing the dust pollution, simplifying a process formulation when PVC (Polyvinyl Chloride) is used for processing products and increasing the transparency, the antioxidant property, the anti-ultraviolet radioactivity of the products; the composite heat stabilizer is non-toxic and reduces the cost; and the composite heat stabilizer is suitable for the processing of the PVC (Polyvinyl Chloride) products such as flexible plastics, water supplying tubular products, plastic injection parts and the like, solves the problems of poor initial dyeing property, poor plasticizing effect, weak impact resistance at low temperature, weather resistance and the like of the traditional single stabilizer and increases the thermal stability of the PVC (Polyvinyl Chloride) products.