Extreme ultraviolet lithography (EUVL) has been regarded as a promising lithographic technology for the 22 nm hp node. It takes advantage of the light of extreme ultraviolet (EUV) whose wavelength is 13.5 nm. But in the 160~240 nm band, laser produced plasma light source spectral intensity, photoresist sensitivity and the reflectivity of multilayers are relatively large in the EUVL. The exposure of photoresist will reduce the lithographic quality in the out-of-band. It demonstrates that both theoretically and experimentally, coating the SiC layer on the Mo/Si multilayer can effectively suppress the out-of-band radiation. Designing and fabricating ［Mo/Si］40 SiC multilayers take advantage of X-ray diffraction, spectroscopic ellipsometry, vacuum ultraviolet (VUV) spectrophotometer to determine the thickness and optical constants of thin films and the reflectivity of multilayers. The reflectivity of the out-of-band reduces to 1/5, while the reflectivity of in-band only 5% reduction.