Metasurface is composed of many sub-wavelength metastructures that can be fabricated in a flat surface using CMOS process. Light can be precisely controlled by a metasurface through the specificly designed shape and arrangement of metastructures. This enables metasurfaces to realize same funcitons as conventional optical devices. In recent years, metasurface-based flat optic devices have attracted great attention since they are ultrathin, ultralight, mass-producible, and can be monolithically integrated with other optoelectronic devices. Ultraviolet photolithography based wafer-level fabrication has been considered as one of the most promising approaches for the mass-production of metasurface-based flat optic devices. In this article, recent progress in wafer-level metasurface-based flat optics is reviewed. Optical devices such as metalens, polarization bandpass filter, half-wave plate, perfect absorber, and beam deflector are demonstrated on different types of wafers with various diameters.