Abstract: Zeta potentials of cement particles and relative wetting contact angle were measured by means of electrophoresis and capillary ascending methods respectively. The effect of polyethylene glycol(PEG) on the surface property of cement particles has been inspected, which facilitates further studies on the relationship between the surface property and selective permeability. Experimental results indicate that the relative water wetting increases rapidly with only a minor change of the negative zeta potential of ~cement particles when PEG concentration is lower than ~0.01 , which causes rapid increase of the water relative permeability. With the increase of PEG concentration, zeta potentials and the water relative permeability decliner, while the oil relative permeability changes smoothly.