This paper describes effect of blending of poly(trifluoropropylmethylvinylsiloxane) (PTFPMVS) with polydimethylsiloxane (PDMS) on the surface properties of the blend, such as hydrophobicity. The surface molecular mobility of the PDMS/PTFPMVS blends was investigated via dynamic contact angle measurement and adhesion tension relaxation. Surface resistance of the blends was also measured under the continuous of salt fog spraying. The advancing contact angle of the PDMS/PTFPMVS blends increased with increasing content of PTFPMVS, but the receding contact angle decreased. We found that a flexible side-chain segment having greater surface energy of the PTFPMVS could be reoriented easily in water to decrease the interfacial tension of the polymer/water interface. This surface functionality seems to play a major role in the decrease of receding contact angle and the surface resistance of PDMS/PTFPMVS blends during wet electrical aging.