The invention discloses an application method of a wavelet singular entropy in periodic fault detection of a stacker. Wavelet transform is performed on a signal from a stacker to obtain wavelet coefficients at different wavelet scales corresponding to different wavelet frequency bands, and the wavelet coefficients form a wavelet coefficient matrix; singular value decomposition is performed to obtain a series of singular values capable of reflecting basic features of an original coefficient matrix, so that distribution of all components is realized and the distribution of all components is obtained; and then on the basis of statistical properties of an information entropy, uncertainty analysis is performed on a singular value set to provide a certain measure for the original signal and themeasure is used as a fault signal feature. With the disclosed method, the signal characteristics of periodic faults can be extracted from the original signal quickly; and the fault feature extracted based on the wavelet singular entropy is independent of the fault amplitude.