The thermal stability and light resistance of polyvinyl chloride are poor. Hydrogen chloride was first decomposed at 150 ℃, and the adverse reaction occurred with the amount of plasticizer. In addition, the effect of the pigment on PVC, reflected in the pigment and PVC and the composition of PVC products and other components of the reaction and pigment itself resistance to mobility, heat resistance. Some of the ingredients in the coloring agent may induce degradation of the resin. such as iron ions and zinc ions are catalysts for the degradation of PVC resins. Therefore, the use of iron oxide (red, yellow, brown and black) pigments or zinc oxide, zinc sulfide and de-tak powder white pigment will reduce the thermal stability of PVC resin. Some colorants may have a effect on the degradation products of PVC resins. such as ultramarine pigments acid resistance, so in the process of PVC coloring, and PVC decomposition of hydrogen chloride produced by the interaction between the loss of due color. Therefore, in the case of PVC coloring, taking into account the characteristics of resins and related auxiliaries, combined with the characteristics of pigments. The following problems should be paid attention to when choosing coloring agent.