The invention relates to the metallurgical material liquid potential online detection technology field and discloses a fluid potential detection device. The device comprises an elevating device, a potentiometer assembly, a flushing apparatus and a control apparatus. In the invention, the elevating device drives the potentiometer assembly to move up and down so as to realize that the potentiometer assembly leaves a solution timely so that a condition that the potentiometer assembly is immersed in the solution for a long time is avoided and risks of scale formation and pollution are reduced; the flushing apparatus is used to carry out regular flushing on the potentiometer assembly, a surface of the potentiometer assembly is kept to be clean, scale formation of the potentiometer assembly is avoided and the potentiometer assembly is prevented from being polluted so that the potentiometer assembly accurately monitors an oxidation reduction potential of a chemical reaction in the solution and accurate information support is provided for carrying out optimization control on a later metallurgical process reaction. Besides, a sensitivity of the potentiometer assembly can be guaranteed, a service life of the potentiometer assembly is prolonged, increased of a measurement error is prevented, and production cost and energy consumption during a production process are controlled.