Abstract: With the advancement of new power system construction, distribution grids are gradually evolving from networks solely receiving and distributing electricity to users into power networks that integrate and interact with generation, transmission, load, and storage, while flexibly coupling with higher-level grids. To better support high-quality grid development, enhance main-distribution grid coordination capabilities, and ensure grid supply reliability, research on a quantitative evaluation system and methodology for main-distribution grid coordination has been conducted. This paper establishes a quantitative evaluation system for main and distribution grid coordination encompassing three dimensions and one integrated framework: coordinated power supply capacity, coordinated grid structure, coordinated equipment utilization, and coordinated substation-line matching integration. This system precisely identifies weak links in regional grid coordination between main and distribution grids, thereby promoting the development and enhancement of main-distribution grid coordination planning technologies.