With the upgrading and transformation of high‐tech industry, China has shown a certain capacity of technology diffusion in some technological fields. Based on the theory of technology diffusion, this paper divides the countries along the Belt and Road into 5 regions, uses the patent citation data of the countries along the Belt and Road from 2005 to 2019, combines the 5 technology fields and 35 technology sub‐fields of PCT patent classification, and studies China's technology diffusion to each region and the relationship between technology diffusion fields. The research results show that after the Belt and Road Initiative, technology diffusion in the countries along the Belt and Road has increased more, and the technology diffusion in the field of electrical engineering in Southeast Asia is the most, the technology diffusion in the field of chemistry in South Asia is the most, and the technology diffusion in the field of West Asia and the Middle East is more extensive and balanced.