The neutral point through the low-resistance grounding system is applicable to the distribution network with majority of cables. However, due to the complicated environment of the distribution feeder, single-phase high-impedance ground faults cannot be detected rapidly and sensitively by existing zero-sequence overcurrent protection. To solve this problem, this paper analyzes the relationship between the zero-sequence current and the zero-sequence voltage of faulty line and healthy line, and seeks different fault characteristics between them. A protection algorithm based on the waveform similarity between the line zero-sequence current and the bus zero-sequence voltage differential is proposed. Sampling the zero-sequence current and the zero-sequence voltage of the line, the proposed method judge whether a single-phase ground fault occurs on the line by comparing the waveform similarity between the line zero-sequence current and the bus zero-sequence voltage differential value, which can greatly improve the sensitivity of ground fault protection. Finally, the effectiveness of the algorithm is verified by PSCAD simulation.