Abstract: A series of stearic acidintercalated Ca/Znrareearth hydrotalcitelike compounds were synthesized by a coprecipitation method. Structures of the resultant products were characterized by powder Xray diffraction and Fouriertransform infrared spectroscopy. Thermal stability of poly(vinyl chloride) (PVC) compounds containing different contents of the hydrotalcitelike compounds was evaluated by means of Congo red test, thermal aging oven and conductivity methods. Rheological and mechanical properties were investigated on the optimized PVC compounding system. The results indicated that this type of hydrotalcitelike compounds enhanced the thermal stability of PVC due to a synergetic effect, and therefore, the PVC compounds achieved a dramatic increase in thermal stabilization time. Moreover, the colors of PVC compounds were effectively restrained in early thermal aging stages. The optimal weight ratio of calcium hydrotalcitelike and zinc hydrotalcitelike compound was 2.25:0.75. Compared with normal Ca/Zn stearate, the hydrotalcitelike compounds can more effectively enhance the thermal stability, and rheological and mechanical properties of PVC.