Abstract: Taking a south-facing windowed experimental room in Changsha as the research object,a numerical model of radiant floor combined with fan-coil cooling system is established using EnergyPlus energy consumption simulation software and the reliability of the model was verified by experiments. Through calculating by standard and simulation analysis,the influence of solar radiation heat under different window-wall ratios on the cooling capacity of the radiant floor and the design capacity of the fan coil system is quantified;a simplified method for predicting the capacity of the radiant system under solar load and is proposed.