Abstract: In this paper, stearic acid , γ - aminopropyl triethoxysilane (KH550), and aluminate coupling agent were introduced into soft PVC. The effect of the modifiers on activation index, oxygen index, mechanical property, hardness, and micro morphology were studied. When the content of stearic acid was 1.5 phr, that of the stearic acid modified aluminum hydroxide was 20 phr,the material provieded a comprehensive performance, and the oxygen index increased by 2.7%.