The influence of water cement ratio, polymer emulsion and air entraining agent on the change of cement mortar resistivity with capillary water absorption time was studied by four electrode method. The study shows that with the increase of capillary suction time, the resistivity of cement mortar is lowered down, then decreases rapidly, then remains stable; capillary suction can make the resistivity of cement mortar decrease by more than 70%, which may be related to the pore water after the mortar is formed inside the conductive channel; increasing the water cement ratio and mixing air entraining agent can greatly improve the resistivity of mortar under drying condition, and also have a certain effect on the resistivity of mortar under the condition of water absorption, but have little effect on the resistivity of mortar after water absorption, and the incorporation of 6% polymer emulsion can not only improve the resistivity of dry conditions, but also improve the resistivity of mortar after absorbing water(up to about 4 times, and higher than 360Ω·m), these may be related to the effect of the water cement ratio, polymer emulsion, air entraining agent on capillary pore structure of mortar.