Hospitals play a crucial role in promoting public health and well-being, but their distribution and accessibility can significantly affect healthcare outcomes. The Guangdong-Hong Kong-Macau Greater Bay Area (GBA) boasts an abundance of healthcare resources; however, access to these facilities can be challenging due to population clustering and inadequate resource allocation. Unfortunately, quantifying residents' access to healthcare is complicated by the lack of a centralized database and complex transportation systems. To address these limitations, we developed a comprehensive healthcare facility dataset comprising 54,902 sites, utilizing internet maps' precise location services. Furthermore, we developed a novel framework for real-time driving-based path planning that integrates facility geographic coordinates and population density data. Our analysis revealed that 6.7% (4.8 million people) could not reach a healthcare facility within 30 min. Even after accounting for rural clinic facilities, 2.5% (1.8 million people) remained unable to access healthcare, mainly in peripheral cities. Finally, we simulated a scenario in which 12 new hospitals were added to demonstrate the effectiveness of reasonable hospital placement in improving healthcare accessibility. By investigating GBA's experience, we can derive best practices, pinpoint areas for improvement, and inform policy development aimed at enhancing healthcare accessibility for all residents. Our findings can serve as a blueprint for other provinces in China and provide insights into healthcare accessibility and resource allocation strategies for other nations with similar hierarchical healthcare systems.