The effects of silane coupling agent on the performance properties of cotton fabrics treated with loess and its washing durability were investigated. Mean average diameter of loess was $17.88mu{m}$ and main components were $SiO_2,;Al_2O_3;and;Fe_2O_3$. By using the cationic agent, the dyeability of cotton fabrics was improved. The washing durability, antibacterial property and deodorization rate were improved and very good emissivities of far infra-red rays were obtained by using the silane coupling agent. And also the mechanical properties of cotton fabrics, such as primary hand values, were improved.