External harmonic currents will cause each harmonic source of harmonic responsibility proration inaccurate.For the purpose of accurately assessing harmonic responsibility of the harmonic source of concern,the method based on sample datas of assessing harmonic current responsibility is proposed.At first, using Norton equivalent circuit schematic, the system and the customer is equivalent harmonic impedance and current sources in parallel.Then the harmonic current contributions og customer though the harmonic Norton’s equivalent circuit model of the system constructed on the basis of the Real-time sampling of voltage and current data. A simulationl model with three harmonic sources is established Results indicate that,the proposed method apportions well the harmonic current responsibility among multiple users,with improved accuracy.