Abstract: PVC extrusion and injection is greatly affected by material uniformity.Poor material uniformity will results in defects such as particles,wrinkles,and lines.Customer satisfactory and manufacturing efficiency will be enhanced by improving material uniformity.Selecting material uniformity index,analyzing present uniformity and improving manufacturing are included in the article.The evaluate index of PVC material uniformity is studied with ANOVA.Ash rate is selected as material uniformity index with ANOVA result.Status of material uniformity is analyzed with hypothesis test.Material uniformity is not stable with hypothesis test.TRIZ and central limit theorem are applied to improve material manufacturing process,Mixing process is added to solve the problem.