As one of the important development directions of new energy resources, hydrogen, compared with traditional fossil fuels, has the significant advantage of high calorific value, pollution free, wide source of supply and is renewable. It is called clean energy of the future and will become a new way for mankind to deal with the worsening energy issues and environmental situations in the future. Hydrogen transportation is an important part of hydrogen energy utilization. The use of reliable pipeline transportation to connect hydrogen gas sources with target users is the key to optimize energy consumption and promote the utilization of hydrogen energy. Compared with the high-purity hydrogen pipeline, the hydrogen blended natural gas pipeline has the characteristics of flexible resource allocation and high resource utilization rate, which can be used for the blending of upstream hydrogen products into adjacent natural gas pipelines and realize the transportation of multiple media in the same pipeline. This will be a popular way to transport and utilize H₂ resources in the future. Hydrogen, as a quantum gas, is difficult to compress, mix, and store. At the same time, hydrogen leaks easily, and has a wide range of explosion limit (4% to 75%). When natural gas is blended with hydrogen, the mixture is much more complex and attention must be paid to its safety in design. Based on the physical properties of hydrogen, combined with the analysis of the existing issues of hydrogen-blended natural gas, this paper compares the safety in design with conventional natural gas pipeline, and provides an in-depth analysis for the safety in design of hydrogen-blended gas pipelines, in order to further reveal the laws of nature. The research results show that there will be obvious component stratification upon the shutdown of hydrogen blended natural gas distribution equipment and pipelines; the design of the venting of the hydrogen-blended natural gas pipeline shall have to avoid auto ignition of the vented gas. There is still much work to be done on the safety in design of hydrogen blended natural gas pipelines. The results of this study can provide relevant references for the safety in design of hydrogen-blended natural gas pipelines.