Knowing deformations and stress-stress fields of a rubber boot at large joint angles is a key factor (* ) in the design. Determinations of the deformations and strains used to depend on experiments. It would contribute greatly to the improvement in the development efficiently, if such experiments could be substituted by numerical analysis. It is,however, difficult to analyze the rubber boot,due to the particular mechanical properties of the rubber materials and the complex three-dimentional contacts with the shaft and the boot itself accompanying such parts. Difficulties involved in the analysis are finally about to be solved by 5 measures.