Abstract: It is not reliable that using empirical method to determine safety coefficient of configuration in designing of the rubber of chuck.Through the finite element analysis,the stress analysis was carried out on the rubber,find out the factor which affect the stress and deformation of the rubber remarkably,constructing a more reasonable design project.Resultsindicated that decreasing the outdiameter of rubber and increasing its length and shoulders inverted angle can improve the stress state of the rubber,in which the configuration of the chuck was predigested and the reliability of the chuck was enhanced.