Abstract: The development of the clean, safe, efficient and widely sourced hydrogen energy is very important for the construction of low-carbon and clean energy structure system. Hydrogen-blended transportation in natural gas network is an integrated energy system with higher comprehensive degree. By blending hydrogen into the natural gas network, efficient and economic large-scale hydrogen consumption and long-distance transportation can be realized. In this paper, two key problems of hydrogen-blended transportation in natural gas network were proposed. A simulation method of hydrogen-blended transportation in natural gas network considering transient characteristics of blending process and distribution parameter characteristics of transportation process, and a scheduling method of hydrogen-blended transportation in natural gas network considering constraints of pipe material, gas network equipment and user terminal equipment were proposed. On this basis, the blending characteristics, transportation characteristics, transient characteristics, condensation and permeability characteristics of hydrogen in existing literature and the influence of hydrogen-blended natural gas on pipes and equipment were summarized. Finally, the existing hydrogen blending demonstration projects in the world were summarized, and the future research direction of hydrogen mixing transportation in integrated energy natural gas network was proposed.