Abstract: In this paper, hydrocalumites based on CO32- were prepared from calcium hydroxide, aluminum hydroxide, and anhydrous sodium carbonate, deionized water was used as a solvent. The product was analyzed by FI-TR, XRD and SEM and used as a thermal stabilizer in PVC. Through the methods of thermal aging test, Congo red test, conductivity test, and TGA, the thermal stability was measured. It showed that the Ca4Al2(OH)12CO3·5H2O constituted a long-term thermal stabilizer for PVC. When 3 phr in PVC, the thermal stable time could continue to 70 min and its static thermal stabilization time could be 52 min. When the amount of complex systems of Ca4Al2(OH)12CO3?5H2O/ZnSt2/DMAU was 3 phr and the mass radio of the system was between 3：0.5：1.5 to 3：0：2, the early whiteness of complex system could be up to 60 min. Even to about 110 min, it would not appear "zinc burn."

Key words: hydrocalumites, poly( vinyl chloride), thermal stabilizers, complex