A method for predicting the concentration of aluminum oxide in an electrobath relates to a real-time control for the concentration of aluminum oxide by using a bath control machine real-time measuringand displaying the concentration of aluminum oxide in an electrobath. The method is characterized in that: the real-time predicting process is using the bath control system and the voltage of the real-time detecting electrobath and system current and controlling the discharging interval, the time and the discharging capacity parameter to build an electrobath operating parameter and a relation mode of the aluminum oxide concentration and then predicting the concentration of aluminum oxide in an electrobath and displaying the real-time aluminum oxide concentration on the bath control machine. The method of this invention is suitable for the intermediate point type discharging pre-bake aluminum electrobath of the 70kA-350kA series. This method can control the prediction of the concentrationof aluminum oxide in aluminum and it is beneficial to the production technique and operating stuff to timely know the operating state of the electrobath which is a benefit for the management and control for the production of electrolytic aluminum.