In order to improve the detection accuracy of harmonics/interharmonics in power harmonic signals, a new detection method based on variational mode decomposition (VMD) and Teager energy operator is proposed. Firstly, the correlation coefficient method is used to determine the modal decomposition number in the VMD algorithm. Secondly, the VMD is used to decompose the harmonic/interharmonic signals to obtain a series of IMF components. Finally, the Teager energy operator is used to make the demodulation analysis of the IMF components. The analysis can obtain the instantaneous amplitude and frequency of the component. According to the instantaneous frequency mutation point in time frequency diagram, the start and end time of transient harmonics/interharmonics can be accurately located. In the case of low signal-to-noise ratio, ensemble empirical mode decomposition(EEMD) and VMD are combined with Teager energy operator for harmonic/interharmonic detection. The simulation experiments comparison show that the proposed method can effectively separate the steady-state and transient harmonic signals, and has higher detection accuracy and better noise robustness.