The invention discloses a Ca / Zn composite stabilizer which comprises components in parts by mass as follows: 14-19 parts of calcium stearate, 11-16 parts of zinc stearate, 2-6 parts of beta-diketone compounds, 0.5-3 parts of beta-diketone metal complexes, 8-13 parts of stearic acid, 0.5-5 parts of polyol, 6-11 parts of hydrotalcite, 0.5-4 parts of phosphite ester, 0.5-4 parts of an antioxidant, 2-6 parts of calcium carbonate and 3-6 parts of polyethylene wax. The beta-diketone metal complexes are directly added to a Ca / Zn composite stabilizer system, by means of increase of the effective concentration of the beta-diketone metal ion complexes of the stabilizer in PVC (polyvinyl chloride) thermal stabilization, the synergistic effect is promoted, and the thermal stability of the Ca / Zn composite stabilizer is improved.