Abstract: A new crosslinking agent containing silicon-hydrogen atoms and trimethoxylsilicon groups was synthesized by controlling the molar ratio of 2,4,6,8-tetramethylcyclotetrasiloxane to vinyltrimethoxyl-siloxane to be 1:2.A PMDS hybrid membrane was also prepared by using the crosslinking agent,a silicone rubber containing vinyl groups of 10% (molar fraction) and tetraethoxysilicone(TEOS) were chosen as the matrix materials.There were three types of the crosslinking reactions involved in the membrane-forming process.These included an addition reaction between the silicon-hydrogen atom and the vinyl group,hydrolyzation and condensation between trimethoxylsiloxane and TEOS and their self hydrolyzation and condensation.The chemical structures and morphologies of the hybrid membranes were characterized by using FTIR and SEM.The mechanical properties were also measured.The hybrid membrane containing a mass fraction of 25.0% of TEOS showed a good membrane-forming property,better optimal mechanical performance and oxygen-enriching property.For example,at 30℃ and 0.05 MPa,P_O2 and α_O2/N2 were 3.7×10⁷ Pa Barrer and 3.45,respectively,which are higher than the target of modified silicone rubber membranes at present: P_O2 >1.0×10⁷ Pa,α_O2/N2 >3.0.