High-power electronization ratios and high cable ratios in urban distribution networks Harmonic pollution is exacerbated from the two aspects of a harmonic wave source and harmonic transmission. The capacitive characteristics of the cable move the resonant frequency to a lower frequency, increasing the probability of system harmonic resonance. Harmonic resonance is an inherent property of a power system that occurs from time to time and jeopardizes the safe operation of the system in severe cases. However, not all harmonic resonances affect the safe and stable operation of the system. In this context, a quantitative assessment method for power system harmonic resonance based on actual measurements is proposed. First, mining factors affecting harmonic impedance are identified on the basis of an equivalent model of a power system. Then, considering the system voltage limit, the level assessment of harmonic resonant amplification is realized in combination with the harmonic impedance. Furthermore, to solve the harmonic impedance more accurately, the complex independent component analysis method is improved on the basis of the harmonic impedance constraint matrix. Compared with the existing methods, the proposed method only needs waveform data of the voltage and current at the common junction point, shows strong adaptability when the system background harmonic fluctuation is large, and can reliably achieve harmonic resonance quantification and level evaluation. Both the simulation and measurement results demonstrate the effectiveness and reliability of the proposed method.