In order to solve the limitation of traditional frequency-domain analysis in Al interconnection electromigration noise, the multiscale entropy (MSE) method is proposed to analyze the electromigration noise time series. The result shows that at the early stage, electromigration noise is irregular, the noise complexity is large, and with the occurrence of nucleation, the electromigration noise becomes more regular, and the complexity decreases obviously. It indicates that the disorder degree of electromigration system decreases continually. Compared with traditional parameters, MSE can be used to successfully characterize electromigration process.