Abstract: The effects of hydrophobic fumed silica (TS-530) and hydrophilic (M-5) on the reinforcing and the thermal stability of the RTV-1 silicone rubber were studied, so were their dispersibilities in the rubbers.The results showed that the hydrophobic fumed silica hasa better reinforcing effect and dispersibility in ketone-oxime RTV-1 silicone rubber, and when the addition was 20 ~ 25 phr, the reinforcing effect was better; the thermal stability of the rubber added in TS-530 was better than that added in M-5.