Abstract: SIFEL 3705 is a kind of liquid fluoroelastomer developed by Shinyue company, Janpan, which can resist many chemicals and strong reducing media. It has been widely used in military, electronic, petrochemical and other fields overseas. It can scientifically guide the selection of sealing materials, give full play to the high performance of the material so as to meet the harsh sealing conditions when the structure and performance characteristics of SIFEL 3705 are mastered. The chemical structure and low temperature resistance of the liquid fluoroelastomer SIFEL 3705A and 3705B premixed were analyzed by FTIR, nuclear magnetic resonance spectroscopy (NMR) and differential scanning calorimetry (DSC) analyses. For the fluoroelastomer prepared by vulcanization of two-component premix, DSC, dynamic thermo-mechanical analysis (DMA), mechanical properties, low temperature flexibility, compression set, heat resistance and chemical medium resistance were tested and analyzed. The results show that the chemical structure of the main compound in SIFEL 3705A and 3705B premix is similar, which is fluororubber with ether bond C—O—C bond in the main chain. The glass transition temperature T_g of the fluoroelastomer is −52.5℃, and it still own resilience at −50℃. The fluoroelastomer has good mechanical properties and heat resis-tance with Shore A hardness of 66, tensile strength of 8.98 MPa, elongation at break of 289%, and initial degradation (mass loss of 5wt%) temperature as 476.8℃. The constant compression set is no more than 20% after compressing at 130℃ for 120 days. Meanwhile, the fluoroelastomer has excellent resistance to chemical media. The performance changes are unconspicuous in anhydrous ethanol and synthetic oil. The properties are changed quickly and then reach equilibrium in strong polar solvent of N, N-dimethylhydrazine. The results show that SHIN-ETSU fluoroelastomer as a sealing material is applicable for harsh environment such as low temperature of −50℃ and strong corrosive solvent.