The composites composed of PVC, NBR and BaSO4 particles were prepared by melt blending method. The mechanical properties, microstructure and thermal stability of the composites were investigated. The results indicated that the elongation at break of PVC was greatly improved by addition of NBR, while the tensile strength was decreased. The elongation at break and the tensile strength of PVC/NBR composites first increased and then decreased with the increasing content of BaSO4, and the maximum were emerged at 5phr BaSO4 addition. The initial decomposition temperature of the composites composed of PVC, NBR and BaSO4 is 10.79°C greater than that of the composites composed of PVC and NBR. The scanning electron microscopy photograph showed that NBR and BaSO4 particles were uniformly dispersed in the PVC matrix when the addition of NBR and BaSO4 particles was low.