Abstract: In order to understand the UNESCO’s open science policy, its characteristics and effectiveness, this paper analyzes the texts of 16 UNESCO’s open science policies using grounded theory analysis. It is found that it includes six aspects: open access policy, open education policy, open cooperation and innovation policy, open science guarantee policy, open science incentive policy, and open source software and source code policy, thus forming a relatively complete open science policy system, which has played a key role in leading the formulation of open science policies in various countries, raising the level of global awareness of open science, and promoting the construction of open science infrastructure. Drawing on the experience of UNESCO, China should set up and perfect the open science policy system, strengthen the construction of the standard of open science infrastructure, set up the evaluation standard and index system of open science, and give play to the unique role of the library in promoting open science, so as to promote the development of open science practice in China.