Rubber tubes under pressure can undergo large deformations and exhibit a particular nonlinear elastic behavior. In order to reveal mechanical properties of rubber tubes subjected to internal pressure, large deformation analysis and stability analysis have been proposed in this paper by utilizing a modified Gent’s strain energy function. Based on the nonlinear elastic theory, by establishing the theoretical model of a rubber tube under internal pressure, the relationship between the internal pressure and circumferential principal stretch has been deduced. Meanwhile stability analysis of the rubber tube has also been proposed and the relationship between the internal pressure and the internal volume ratio has been achieved. The effects on the deformation by different parameters and the failure reasons of the rubber tube have been discussed, which provided a reasonable reference for the design of rubber tubes.