The harmonic source identification problem of power system is abstracted to blind source separation. Using independent component analysis and information theory, propose a new method for power grid multi harmonic sources identification. Independent component analysis method is used to reconstruct the harmonic current while mutual information theory is used to locate the harmonic source. In order to prove exactness of the method, use the IEEE39 nodes simulation to identify multi harmonic sources. Conclusion proves that under the unknown network parameters conditions, the proposed method can accurately identify the location of the multi harmonic sources.