Provided by the present invention are a composite rare earth heat stabilizer for PVC and a preparation method therefor, and the rare earth composite heat stabilizer comprises the following raw material components in parts by weight : 10-70 parts of rare earth salt; 5-65 parts of calcium stearate; 1-15 parts of an antioxidant; 1-6 parts of hydrotalcite; 1- 4 parts of basic calcium aluminum phosphite; 1-8 parts of stearic acid; 3-10 parts of lauric acid; 5-15 parts of isooctanoic acid; 10-15 parts of polyethylene wax; 0.1-2 parts of phosphite ester; 0.5-5 parts of octyl epoxy stearate; and 2.5-20 parts of di-n-octyl phthalate. The rare earth composite heat stabilizer disclosed by the present invention is an environment-friendly stabilizer with high stability and low price, and has broad application prospects.