Abstract: The self-made rubber seed oil-based epoxy fatty acid methyl ester(ERSO) was used as plasticizer and the oil-based polyacid calcium-zinc composite(OMFCTS) was used as thermal stabilizer. Then the combination of ERSO and OMFCTS was used in PVC modification with β-diketone as co-stabilizer. The thermal and mechanical properties of eight modified poly(vinyl chloride) (PVC) blends were determined by means of the heat aging test methods,Congo-red test,TGA,TGA-FTIR,TGA-MS,tensile test and DMA. The results showed that the PVC blends with ERSO/OMFCTS had the optimal thermal stability,good mechanical properties,and lower glass transition temperature(Tg,38.2℃) than that of the PVC blends with DOP/CaSt2/ZnSt2,ERSO/CaSt2/ZnSt2 or DOP/OMFCTS. And its static thermal stability time at 200℃ was 46'21" and the tensile elongation at break was 265.6%. It could be concluded that there was an obvious synergistic effect between ERSO and OMFCTS,and the ERSO/OMFCTS could replace the tradational plasticizer dioctyl phthalate and calcium/zinc stability of stearic acid(CaSt2/ZnSt2) effectively.