Abstract: In response to the demands of deep load regulation in the power grid and to explore the potential of thermal power units, a comprehensive experimental study was conducted on a 660 MW unit.By combining the unit′s operating experience and parameters, its safety and economic performances at low load conditions were objectively assessed.This analysis identified factors restricting the unit′s capability for deep load regulation.Consequently, feasible modifications or optimizations to address these issues were proposed.Practical applications reveal that several factors must be considered to meet the power grid′s load regulation requirements.These include the boiler′s performance at low loads, hydrodynamic stability, pollutant emissions, the steam turbine′s adaptability to low loads, and the power unit′s ability for synchronized automatic control.