A method of manufacturing a sub-wavelength extreme ultraviolet metal transmission grating is disclosed. In one aspect, the method comprises forming a silicon nitride self-supporting film window on a back surface of a silicon-based substrate having both surfaces polished, then spin-coating a silicon nitride film on a front surface of the substrate with an electron beam resist HSQ. Then, performing electron beam direct writing exposure on the HSQ, developing and fixing to form a plurality of grating line patterns and a ring pattern surrounding the grating line patterns. Then depositing a chrome material on the front surface of the substrate through magnetron sputtering. Then, removing the chrome material inside the ring pattern. Then, growing a gold material on the front surface of the substrate through atomic layer deposition. Lastly, removing the gold material on the chrome material outside the ring pattern as well as on and between the grating line patterns, thereby only retaining the gold material on sidewalls of the grating line patterns.