For dividing harmonic responsibility so that dealing with harmonic problems by using economics means, this paper presents a method to identify the harmonic sources based on the data measured by the harmonic measurement devices. According to the connectivity between each nodes, the optimal number and location of harmonic measurement devices are obtained by using the method combined BPSO and index method. Considering a certain modeling and measurement error, it categorizes the suspect buses based on the direction of harmonic power flow, and proposes localization index to rank the bus in order to reduce the field investigation works which is unnecessary. Finally, the IEEE 14 nodes model in ETAP 12.6 is built and the effectiveness of the method proposed is proved.