The invention relates to an on-line identification method for a concentration signal of aluminum oxide in an electrolyte in an aluminum electrolysis cell, and relates to an on-line identification method for a concentration signal of aluminum oxide for controlling the charging quantity of the aluminum oxide in the aluminum electrolysis production process. The method is characterized in that: in the on-line identification process, polar distance is used as an excitation signal, and the concentration of the aluminum oxide is identified by a response signal of cell resistance in the adjustment process of the polar distance. The method has the advantages of high identification speed, small influence on the condition of the electrolysis cell and the like, the accurate control over the blanking of the aluminum oxide can be realized, anode effect coefficients can be reduced effectively, current efficiency can be improved, the stable running of the electrolysis cell can be realized, and energyconsumption can be reduced.