Abstract: In this paper, an LDHs-Ca/Zn-organic tin compound thermal stabilizer was used to modify rigid PVC plastics. Rheological behavior and thermal stability of the modified PVC were studied by dynamic rolling aging, static hot oven aging, Congo red test, chromatic aberration test, thermogravimetric analysis(TG), and torque rheometer. It suggested that LDHs could act as an auxiliary thermal stabilizer in PVC, and had synergistic effect with Ca/Zn-organic tin compound system. SEM and aging experiments showed that 05 wt% LDHs may render dispersive ability and thermal stability.