Abstract:In power systems,different detection methods in terms of stationary harmonic and the different duration are proposed. The principles of wavelet theory are presented.According to the simulation,stationary harmonics detected by wavelet transform are more applicable than wavelet packet transform,while the result of the detection on transient harmonics by wavelet packet transform is better than wavelet transform. Using wavelet transform for stationary harmonic detection and wavelet packet transform for transient harmonic detection is feasible.