In the face of the historical opportunities and challenges brought by the new round of digital technology revolution and industrial transformation, promoting common development and narrowing the technological gap with cutting-edge countries through high-level cooperation is the key path for developing countries to achieve leapfrog development. Based on the “Digital Belt and Road” initiative, this paper reveals the impact mechanism of digital science and technology cooperation on technology catch-up of late developing countries through empirical research on national level data of the “the Belt and Road” from 2010 to 2023. The research findings are as follows: (1) Digital science and technology cooperation among countries along the “the Belt and Road” can help narrow the technology gap with frontier countries and achieve technology catch-up. (2) From the perspective of innovation chain, digital technology cooperation mainly stimulates the “chain innovation effect” and promotes technological catch-up through mechanisms such as enhancing basic research and development, promoting technology transformation, and enhancing technology application. (3) Heterogeneity analysis shows that the driving effect of digital technology cooperation on technological catch-up is significantly present in countries with larger scales and higher levels of digital infrastructure. (4) Further research finds that China, as the core promoter of digital science and technology cooperation in the “the Belt and Road” countries, can play a “lift-up effect” to drive countries along the line to achieve technology catch-up; The reduction of cultural and institutional differences has significantly enhanced China"s “lift-up effect” on countries along the Belt and Road, and this effect is more significant for smaller scale and higher level of digital infrastructure cooperating countries. The research conclusions of this paper provide important enlightenment for building a digital community with a shared future and promoting high-quality joint construction of the "the Belt and Road".