Objective To evaluate the mechanical properties of SEI silicone for maxillofacial prosthesis before and after heat aging and explore its clinical value. Methods Two kinds of silicones, SEI and A-2186, were performed heat aging for 24, 48 and 72 h. The parameters of tear strength, tensile strength, elongation at break and hardness of them were detected under ordinary state and at different time points after heat aging. Statistic comparison and analysis were conducted. Results Tear strength, tensile strength and elongation at break of A-2186 silicone were more favorable than those of SEI silicone under ordinary state, while the parameter of hardness was an exception (P < 0.05). After heat aging and with time progress, tear strength, tensile strength and elongation at break significantly decreased and hardness significantly increased for both A-2186 silicone and SEI silicone (P < 0.05). After heat aging, tear strength and tensile strength of A-2186 silicone were more favorable than those of SEI silicone, while the latter had a minor change in hardness. Conclusion Compared with the worldwide commonly used A-2186 silicone, there is room for improvement in tear strength and tensile strength for SEI silicone. Given the favorable property of minor change in hardness after heat aging, SEI can be used as a prosthetic material for facial soft tissue defect.