Runoff plot is a useful tool for erosion and hydrologic monitoring. Previously, the methods of V-notch weir, flow flume, and tipping bucket have been widely used to measure the runoff and sediment on the slope. Here, we report an automatic runoff and sediment monitoring system developed based on the tipping bucket method. This monitoring system consists of a tipping bucket flow sensor, a distributed water sample acquisition device, and a dot counter. This system can perform the distributed acquisition of runoff and sediment samples and the automatic measurement of runoff at any time point. Compared to the conventional water sample acquisition method and the existing runoff measuring methods, this system is highly automatic, easy to operate and electricity free. Hence, the new system is suitable for field work. This monitoring system can be widely used to monitor the soil erosion process of slope runoff plots, which is characterized by non-pressure, low head, and small flow, under natural and artificial rainfall conditions. Therefore, this system can be widely used on runoff plots for erosion research.