The development and adoption of a unified green building standards across different agglomerations have often been a challenging and ongoing endeavor. On one hand, these standards must be compatible with local building codes and regulations, ensuring that they meet the local compliance checking requirements. On the other hand, they must also address broader sustainability goals, which may not always align with local practices. This tension has contributed to the phenomenon where, despite claims of international applicability, green building standards often focus on macro-level performance rather than fully understanding the actual green performance of buildings. As a result, this leads to regional disparities in green building evaluation. Consequently, existing framework fall short in providing genuine third-party guidance to help building owners identify building performance gap, with the consideration of region-specific factors such as climate, resource availability and community needs. To address the shortcomings in current green building standards and rating system, the BEAM Society of Hong Kong collaborated with the Authority of Qianhai in Shenzhen to create a green building standard applicable in a transborder agglomeration context, known as the Qianhai Green Building Standard. This standard caters to local building regulations and regional conditions in Shenzhen while aligning with the internationally recognized BEAM Plus assessment standard developed in Hong Kong. Through a unified assessment process, the Qianhai Green Building Standard integrates green building assessment practices between Shenzhen and Hong Kong, addressing both the regional building needs and internationally recognized best practices. This paper will explore the planning, development, and implementation of the Qianhai Green Building Standard, aiming to present a new model for green building standard development that allows cities to comply with both local regulations and international standards through a single assessment process.