Harmonic injections on the demand side are a growing threaten to the power quality in the power utilization grid. Harmonic identification is important to improve power quality in large scale power utilization grid. The smart electrical information network can measure the electrical information in the network with distributed smart meters. This distributed measuring network can improve the harmonic identification accuracy. This paper proposed a distributed harmonic identification method using the ChowLiu information tree. The harmonic currents at the Point of Common coupling(PCC) are extracted by independent component analysis. The ChowLiu information tree offers the topological structure of the signals and recovers the magnitude and location of the harmonic sources. A practical testbed for networked measurement is built to verify the proposed harmonic source identification method. Experimental results show that the proposed method can identify the harmonic sources in a high accuracy under networked sensing environment with acceptable real-time performance.