Abstract: Experimental result shows that the electric resistivity of dry sandstone sample decreases slightly during deforming processes. It decreases with hugeamplitude during this process for the samples containing rare water and decreases firstly, then increases and decreases again for the samples containing more water. It changes very small except decreasingat the beginning of deformation for the samples saturated with water. The resulto fmore accurate observation show that before fracturing, the electric resistiv ity risesslight ly for dry sample, keeps decreasing for samples containing rare water, and first increases then decreases for sample containing more water or saturated. These results may present some hints to the characteristic of middle-and short-term earthquake precursors. Some explanation is given to the mechanism of the change of electric resistivity.

Key words: Electric resistivity, Deforming Processes, Influence of water