The detection of electromagnetic signal leakage has many years of history,especially in the EMC discipline,is more important.However,the electromagnetic signal is not stable, transient and weak.These problems have been bothering us for the traditional frequency do- main electromagnetic signal detection technology.A new electromagnetic signal leakage detec- tion technology based on wavelet transform is presented to solve these problems in this paper. This article selects db3 as the wavelet basis function acc...