Abstract: Under the influence of osmotic pressure, the seepage water flow filtered by depressions soil in karst valley, gradually infiltrate downward and finally discharge to karst conduits or underground river through upper karst erosion networks or karst fissures. In this process, the spontaneous polarization phenomenon or self-potential field will form by the ionic conductive materials. Therefore, the study on self-potential can be applied to explore shallow groundwater in karst valley. The study results showed that the self-potentials banded anomalies ranging from -60～-80 mv with about 40 m wide and extending from north to south with "S" shape have been observed just near the center of Longrui karst valley. On the plane view, the self-potential gradient contours present "zero" value anomalies varying from negative to positive near the top of the karst zones. The spatialdistribution of the "zero" value anomalous zones indicates the surface differences and changes of shallow karst development. Taking Line 18 as an example, the self-potentials caused by shallow karst seepage water in Longrui valley follow the potential function distribution, namely the self-potentials have reached the minimum and accordingly self-potential gradients vary from negative to positive with the shape of central symmetry which shows the "zero" value just near the top of the shallow karst zones(station 615). The self-potentials on either side of the minimum gradually weaken until go to zero due to the stations moving away from the karst zone. Shallow caves, dissolved-fissures and fault fractures were exposed at different depths by the hydrogeologic monitoring borehole. Thus it means that the self-potential can be used as an effective geophysical method for detecting shallow karst water.