For the purpose of environment protecting and energy saving, renewable energy has been distributed into the power grid in a considerable scale. However, the consuming capacity of the power grid for renewable energy is relatively limited. As an effective way to absorb the excessive renewable energy, the power to gas (P2G) technology is able to convert excessive renewable energy into hydrogen. Hydrogen-blending natural gas pipeline is an efficient approach for hydrogen transportation. However, hydrogen-blending natural gas complicates the whole integrated energy system (IES), making it more problematic to cope with the equipment failure, demand response and dynamic optimization. Nevertheless, dynamic simulation of distribution parameters of gas–electricity–hydrogen (GEH) energy system, especially for hydrogen concentration, still remains a challenge. The dynamics of hydrogen-blending IES is undiscovered. To tackle the issue, an iterative solving framework of the GEH-IES and a cell segment-based method for hydrogen mixing ratio distribution are proposed in this paper. Two typical numerical cases studying the conditions under which renewables fluctuate and generators fail are conducted on a real-word system. The results show that hydrogen blending timely and spatially influences the flow parameters, of which the hydrogen mixing ratio and gas pressure loss along the gas pipeline are negatively correlated and the response to hydrogen mixing ratio is time-delayed. Moreover, the hydrogen-blending amount and position also have a significant impact on the performance of the compressor.