The main effective factors of the properties of 193nm HR mirrors were analyzed. It revealed that the electricity field strength decreased quickly from the outer layer to the center layer. So the outer layer next to the air side possessed the biggest electricity field strength. The absorption losses of the high refractive index layers were higher than that of the low refractive index layers. The absorption loss decreased sharply with the changing rate related to the ratio of the refractive index of the high-low refractive index materials from the outer layer to the center layer. The surface scattering loss increased proportionally to the ratio of the refractive index of the high-low refractive index materials. But the low ratio of the refractive index would require more layers to gain the certain reflectance which would result in the higher surface roughness and other loss. So it is useful for reduction of the scattering loss to select relatively high ratio of the refractive index. The HR mirrors were designed according to the alternate high- and low-refractive index layers with quarter-wave optical thicknesses. The designing reflectance was more than 98%.