A large aperture random phase plate (RPP) for target-plane laser beam smoothing at 1.06m m wavelength was fabricated, by using large aperture exposure and dilute HF etching processes. The RPP’s clear aperture is f 250mm. The measured average step height is 1.060m m at 5 locations on the RPP, which has a relative deviation of 1.24% to the theoretical value. A focal spot with very sharp edges and nearly flat-top overall envelop intensity distribution was obtained at the focal-plane of a focusing lens. These results show the fabrication techniques for RPP is effective, and is easily scalable to even larger apertures.