By comparing the Regulation of the Primary and Secondary School Library (2003 Edition) and Regulation of the Primary and Secondary School Library (2018 Edition), this paper illustrates and compares similarities and differences in these two books, as well as analyzing reasons for adaption and demonstrating flaws. Based on the analysis and understanding of the two editions, the paper intends to predict and identify the new missions and vision of Regulation, and conclude that the future development and trend of both primary and secondary school libraries as follows: to invigorate primary and secondary school libraries with people-oriented principles; to justify, digitalize, and multiply all library resources; to update reading room and service with modern technology and conduct imbedded teaching service as core innovation; and to regulate and standardize inter-library cooperation, making it a lasting and efficient cooperative mode.