In the new development stage, international technological innovation cooperation based on the "Belt and Road" initiative is an important measure to promote the construction of a new development pattern. Based on the theory of technology diffusion, this paper uses the relevant statistical data of 135 economies around the world from 2008 to 2019 to analyze the effect of China''s technology diffusion on the host country before and after the "Belt and Road" initiative from the perspective of China''s high-tech industry exports. The influence of distance on China''s technology diffusion under the "Belt and Road" initiative, and the difference-in-difference model is used to test this policy effect. The research results show that the "Belt and Road" initiative is conducive to the technology diffusion of China''s high-tech industries, and can promote technology diffusion by increasing the technological proximity to the host country; but at the same time, institutional distance hinders the technology diffusion under the initiative. The research conclusions provide useful reference and inspiration for China to expand the space for international scientific and technological cooperation through the "Belt and Road" initiative under the new development pattern, and to promote high-level opening to the outside world by strengthening technological innovation transfer and knowledge diffusion.