The extensive application of nonlinear power components makes the harmonic pollution situation of power system increasingly severe. To effectively suppress a variety of noise, and accurately detect harmonic and interharmonic parameters, a harmonic detection method based on the synchrosqueezing wavelet transform (SST) and Hilbert transform is proposed. Firstly, the signal in the power system is decomposed into a set of intrinsic mode type (IMT) function components through SST. Then, instantaneous frequency and instantaneous amplitude of each IMT component are calculated through Hilbert transform. At last, the least squares fitting of instantaneous amplitude and instantaneous frequency is calculated to realize the detection of harmonic and interharmonic from the noisy signal. The simulation results verify the feasibility and the effectiveness of the proposed method, which can effectively improve the detection accuracy of harmonic and interharmonic.