According the structure and working characteristics of suspension packer and its sealing device,the sealing principle and working characteristics of the rubber tube in the three kinds of states,free deformation,constrained deformation and stable deformation,were analyzed,while packer was at the packing and operation stages.A theoretical model for the performance analysis of the rubber tube was established.The nonlinear relationship between the material,geometry and stress changes of the rubber tube at constrained deformation and stable deformation stages were analyzed by application of pressure method.The contact pressure model for rubber tube on the sealing interface,and the criterion for judging the rubber tube seal reliability were built.The finite element model for the suspension packer was established,the contact pressure on sealing interface and its distribution was simulated.The simulation results have good consistency with those of the numerical calculation,which proves the validity of the theoretical model.