This paper presents the measurement methods and the experimental results of X-ray conversion efficiency in 1. 2 keV region from Cu and NaF plasma produced by 1.06 and 0.53μm laser. These results showed that X ray conversion efficiency in Cu plasma is 4-5 times as high as that in NaF plasma with the laser intensity in 1×1013—1×1014W·cm-2 and wavelength of 1. 06 and 0. 53μm. The X-ray conversion efficiencies in Cu and NaF plasma produced by 0. 53μm laser are about 2 times as high as that by 1.06μm laser.