Abstract: This paper focuses on the machine-grid coordination test of the world’s first 700 MW ultra-supercritical low-temperature circulating fluidized bed (CFB) unit. By formulating standardized test schemes, accurately collecting key operating parameters of the unit, optimizing valve control logic, and conducting pre-analysis via power disturbance simulation, the core technical difficulties encountered during the test were systematically addressed. The technical strategies and practical experience accumulated throughout the whole test process not only ensured the smooth completion of the unit’s machine-grid coordination test, but also provided solid technical support for the commissioning and grid-connection tests of subsequent large ultra-supercritical CFB units of the same type.