The utility model discloses a river velocity of flow automatic monitoring system, including drift device, remote terminal and/or mobile terminal, the drift device includes balancing unit, waterproof external power supply charge mouth, can, battery, time -recorder, coordinate record appearance, communication module, GPS module, the bottom of can sets up balancing unit, and balancing unit includes balancing weight and flechette -type fin, and is through the whole balance in aqueous of balancing weight holding device, the same with water flow direction through flechette -type fin holding device travel direction, the utility model discloses convenient to use, application scope broaden, can realize river velocity of flow automatic monitoring.