The invention discloses a method for online detecting the content of copper ions and sulfate ions in a copper electrolyte. The method is characterized in that the method comprises the following steps:placing three digital detection probes in the electrolyte of a copper electrolysis tank, respectively online measuring the temperature T, the viscosity [mu] and the conductivity sigma of the electrolyte by using the three probes, returning obtained measurement data to a computer, solving a component equation set in real time by the computer in order to indirectly obtain the copper ion concentration and the sulfuric acid concentration of the copper electrolyte. Compared with the prior art, the method in the invention has the following advantages: (1) rapid, online and simultaneous detection ofthe copper ion concentration and the sulfuric acid concentration is achieved, and big data analysis of factories is benefited; (2) the method is simple, reliable and cheap, onsite installation of a digital temperature measuring probe, a digital viscometer and a digital conductivity meter is only needed, and installation technologies are mature technologies; and (3) setting of the range of the value of every parameter in formulas disclosed in the method makes detection data accurate, and the data can be applied to industrial production.