Abstract: Opening structure silicone rubber foams were prepared by means of the dissolve-separating foaming technology using pore formers with different morphology. Effects of cellular structure and cell diameter on the properties of opening structure silicone rubber foams were studied. The results showed that the stress relaxation and mechanical properties were mainly affected by cellular structure when the density and the matrix rubber were the same. Tensile strength, hardness, compressive strength and stress relaxation properties of silicone rubber foams were increased with the growth of the regularity of cellular structure. Spherical cellular structure can come about better mechanical properties than others. When the cellular structure was spherical, compression stress relaxation and hardness of silicone rubber foams were less affected by cell diameter in a certain range, but tensile strength was increased when the cellular diameter reduced.