Abstract: Study on the relationship between structure and its static thermal stability of PVC. Using GPC, IR, NMR and SEM tests to analyze its structure; And its static thermal stability is characterization by Oven method, Congo red test, TG and so on. The results showed that, the smaller the molecular weight, the more content of allyl chloride and higher ratio of syndiotatic structure, the pooer thermal stability of PVC. On the contrary, the thermal stability is better. And All the static thermal property test results are consistent.