The structural principles of the sensor in “Digital Network Hail Rain Tester” (DNHRT) are introduced. Based on the principles of buoyancy, tipping bucket rain gauge measurement, computer recording, and network transmission, the measurement errors between the theoretical and experimental values are simulated, and such technical issues as the causes of the errors, field observation regulations, and evaporation compensation revision are discussed. The tests reveal that DNHRT has a reasonable and reliable structure and good performance; the experimental results are stable and have negligible measurement errors. The field data indicate that the measured rainfall difference between DNHRT and automatic weather station observations is in an acceptable range. DNHRT has the advantage of real time monitoring of extreme hail events, for it can measure hail and rain separately at the same time, so can play an vital role in the assessment of hail disasters on wild fruits and crops. It can be widely used in the field monitoring network of disasters in agriculture and forestry with the same modernization level as telemetry rain gauges and other remote sensing devices of meteorological elements.