Summary form only given. SiOx coating was deposited on the surface of Lithium ion battery separators by means of electron beam evaporation technique in vacuum evaporator. Hexamethyldisoloxane (HMDSO) was ionized by plasma and doped into the SiOx coating during the deposition process. The thermal performances of the separator were tested by TGA (Thermogravimetric Analysis), DSC (Differential Scanning Calorimetry) and TMA (Thermal Mechanical Analysis). The wettability was measured by water contact angle. There is no significantly reduction for the mechanical performance of the membrane after coated the as-doped SiOx. The thermal shrinkage is significantly improved, and the heat resistance and the wettability increase to some degree.