The Project on Grass-roots Science Popularization is the first science popularization special plan established by the state through central financial transfer payments. Since its implementation in 2006，the Project has focused on meeting the needs of grass-roots science popularization and solving the problem of“the last kilometer”of science popularization services. The results show that the Project on Grass-roots Science Popularization has experienced four stages of initiation，expansion，transformation，and deepening. The evolution of policy is characterized by the synergistic progression of both mandatory and induced elements，with central-local collaboration and social participation working in concert to continually achieve the dual goals of enhancing grassroots science popularization efficiency and promoting social equity. The process of policy evolution exhibits an intertwining of policy instrument innovation and path dependency，revealing structural contradictions in resource allocation efficiency and a pattern where policy effectiveness is constrained by the quality of institutional supply. Furthermore，we also construct a three-dimensional breakthrough pathway encompassing“institution-technology-society，”aiming to better realize the objectives of institutional change.