Aiming at the problem that the corrosion rate of atmospheric tank bottom is unknown and can only be predicted by experience, the acoustic emission data and magnetic flux leakage detection data of tank bottom corrosion are comprehensively analyzed, and a quantitative evaluation method of tank bottom plate corrosion based on on-line acoustic emission is proposed. Through 100% magnetic flux leakage detection of the tank bottom plate, the risk curve of corrosion of the tank bottom plate is obtained, so as to calculate the corrosion risk pace (CRP). Before opening the tank, the acoustic emission detection of the tank bottom plate is carried out, and its acoustic emission activity is analyzed, so as to obtain the relationship between acoustic emission activity and the corrosion risk pace, and infer the relationship between corrosion risk pace and actual maximum corrosion pace, so as to establish a quantitative evaluation model of the tank bottom corrosion based on acoustic emission detection. At the same time, the influence of actual working conditions and site environment is fully considered to infer the management corrosion pace, which provides the basis for the decision-making of storage tank management and maintenance.