The x-ray phase grating made on silicon wafer was designed under considerations of the parameters of the phase contrast imaging system, the spatial coherence characteristics of x-ray source and its diffraction efficiency for x-ray of 40—100 keV, which is usually used for phase contrast imaging in laboratories and hospitals. The phase grating with diameter of 5 inch , pitch of 5.6 μm, wall width of 2.8 μm and depth of 40—70 μm depending on the energy of x-ray photon, was fabricated using the technique of photo-assisted electrochemical etching developed in our lab. Two special methods, namely, the enhancement of the voltage applied to the silicon wafer and modification of the current density defined by Lehmann formula, have been used to reduce the lateral etching. A reproducible technique has been developed for fabrication of precise and large x-ray phase grating on silicon wafer.