The invention discloses a waste water online biological monitoring method and a waste water online biological monitoring device, and belongs to the field of waste water online monitoring. The device consists of a
circulating pump (3), a
liquid storage chamber (2), a circulation chamber (1), an inductive
electrode (4) and a
multimeter (5); the
circulating pump is arranged at the lateral bottom of the
liquid storage chamber away from the circulation chamber, and is connected with the circulation chamber via a plastic
pipe; the sidewall of the circulation chamber is connected with side surface of the
liquid storage chamber at the equal height to realize flow
exposure of the whole course. Two pairs of
copper electrodes with nuts are arranged on the inner side of the circulation chamber, wherein one pair of the electrodes functions as an input end of an electrical
signal, and the other pair of the electrodes is connected with the
multimeter to form an output end of the electrical
signal. The distribution of an
electric field in the circulation chamber can be influenced by swimming of the tested
organism daphnia, namely the change of output current or
voltage. By the invention, whether the quality of the discharged water is safe can be intuitively reflected; meanwhile, an 'electronic eye' is provided for the
pollution incident monitoring and the dispute resolution monitoring of an
environmental monitoring department. The device disclosed by the invention is simple in structure and strong in mobility and can be used indoors and outdoors.