The invention relates to a water level observation system for achieving automatic detection. The water level observation system comprises a power supply, a mechanical part, a control part and a data acquisition part. The water level observation system is designed and manufactured by applying a water body buoyancy force principle, the water surface position is determined by utilizing buoy gravity and a buoyancy force balance point of the buoy gravity, and a buoy can flexibly and accurately move along with the water level change. The water level observation system acquires and records buoy movement information in real time so as to complete water level observation work. The water level observation system can achieve automatic control through a control circuit and an electromagnetic clutch, accordingly manpower expenditure is reduced, the electromagnetic clutch is started by transient current output by a PLC and controls return of a braking wheel, and accordingly automatic downward movement and balance are achieved. A line concentration wheel is driven by a motor to rotate, and accordingly the buoy upwards moves and automatically stops moving when being subjected balance force. Due to the fact that the electromagnetic clutch is only transiently started, energy consumption can be reduced, and burning loss of a circuit due to overheating can be prevented.