In the perspective of the electricity sector， a method of using load nonlinearity characteristics to identify harmonic sources and assign the responsibility of all the harmonics is proposed. By developing the load time domain equivalent model， with no knowledge of the load parameters on the system side and user side， differential equations are derived using the physical relationship between voltage and current on the point of common coupling（PCC） to solve the load equivalent impedance parameters. The harmonic sources are located according to the load equivalent impedance parameters identified. The singular value decomposition（SVD） method is adopted to analyze the sample voltage and current data， overcome the impact of measurement noise and the measurement matrix singularity， and improve the accuracy of parameter identification. Furthermore， quantified load non-linearity is used to further distinguish between the responsibilities of all harmonic sources. Simulation results show that the method proposed is simple and efficient， and capable of accurately locating harmonic sources while free from background harmonic influence.