A transmission grating with an area of 1 mm × 1 mm, a pitch of 300 nm, and a gold thickness of 1 μm for X-ray imaging and microscopy is successfully fabricated by combining electron beam lithography, X-ray lithography, and electroplating. Firstly, a high-density mask in pitch of 300 nm and gold thicknes of 250 nm for transmission grating is originally patterned on the Si3N4 membranes by electron beam lithography and electroplating. Then, the X-ray lithography and electroplating are used to replicate the transmission grating with the profile thickness of 1 μm, aspect ratio of 7, and the duty cycle about 1∶1.Experimental results show that the fabrication method combining electron beam lithography,X-ray lithography and electroplating has advantages over other fabrication methods in big pitch,nanometer scale and straight side well for transmission grating.