The invention discloses a method for continuous on-line detection of quality of complex and varied water and belongs to the technical field of water quality detection. The method comprises positioning, balance, continuous power supply, detection and data acquisition. A wing pendulum is installed below a waterline in the side of a buoy main body, fits to an equal-weight probe well and keeps the balance of the buoy main body. Through setting the swinging range of the wing pendulum, the wing pendulum faces to a water flow. When flood impacts, directions of the water flow and wind are changed sharply, the wing pendulum is influenced by action and reaction and forms resistance so that buoy main body movement and rotation are prevented, stability is improved, the balance and direction are kept,the probe is protected and real-time sampling and testing are guaranteed. The method solves the problem that the device for detection of quality of complex and varied water has high requirements and is easy to capsize.