The admittance amplitude of inter-harmonic sources to ground is very small, so traditional parallel resonance analysis generally ignores the admittance of inter-harmonic sources to ground. However, if the admittance of inter-harmonic sources to ground has a greater influence on the parallel resonance to a high degree, ignoring the admittance of inter-harmonic sources to ground couldseriously reduce the accuracy of the parallel resonance analysis results.In order to prove the necessity of the parallel resonance analysis to include the admittance of inter-harmonic sources to ground, this paper establishes a parallel resonance test system based on the IEEE-33 nodes distribution network model, and carries out the research on the influence of admittance of inter-harmonic sources to ground on the parallel resonance of distribution network.Based on the modal analysis method, it is found that the admittance of inter-harmonic sources to ground at a specific node can significantly affect the parallel resonance. Through sensitivity analysis, it is found that the admittance imaginarypart of inter-harmonic sources to ground at a specific node has a greater influence on the high degree to the parallel resonance, which revealsthe reason why the admittance of inter-harmonic sources to ground can obviously affect the parallel resonance, and finally validatesthe necessity of including the admittance of inter-harmonic sources to ground in the parallel resonance analysis of distribution network.