This study examines the implementation and impact of the ACM-THU Open transformative agreement at Tsinghua University. Quantitative content analysis of 1,317 ACM publications from 2021 to 2024 by Tsinghua authors reveals that the ACM-THU Open agreement has effectively increased open access publishing, with all articles in 2022 and 2023 being openly accessible. However, challenges remain in author engagement and copyright licensing, as 35% of 2024 publications still used non-Creative Commons (CC) licenses. The study also investigates the relationship between open science practices and research impact. OA articles had significantly higher download counts than non-OA articles, regardless of the presence of open data, code, or materials. Among articles without these open practices, OA status was associated with higher citation counts, but this difference was not significant when open data, code, or materials were present. The findings underscore the impact of various open practices on research visibility and citation advantage. The results suggest that universities should adopt a multifaceted approach to support the implementation of transformative agreements and foster the advancement of open science. This includes establishing stronger mandates for CC-BY licensing, conducting targeted outreach to researchers, and developing integrated information systems to monitor open access compliance and align research practices with institutional open science strategies.