The invention provides a high-resolution hydrological monitoring method for a small-drainage-basin karst water system. Hydrological monitoring of a rainfall, surface water, an underground water flow,and a water level high resolution of a karst water system of a tunnel zone is carried out and the monitoring data are transmitted to a terminal processor in real time for convenient extraction and utilization; dynamic flow characteristics and changing rules of different karst aquifers, different karst landforms and karst water systems in the tunnel zone are studied and surveyed, an infiltration coefficient and a flow lag changing law of each sub-basin are monitored accurately to provide important hydrogeological data for prediction of tunnel water inflows, so that a critical role in segmentedprediction of tunnel water inflows is realized. Therefore, the monitoring work efficiency and automation level are improved; a lot of manpower and material costs are saved; the monitoring method has the low engineering load and the low cost; and the influence on the local environment is minimized. The high-resolution hydrological monitoring method is suitable for tunnel water inrush prediction inkarst areas, especially in segmentation prediction.