For the fabrication of Schottky barrier diode working under Terahertz(THz) frequency, the whole fabrication process of planar Schottky barrier diode is studied, especially on materials growth, ohm contact, fabrication of anode, trench etching. Suffer layer and epitaxial layer are grown on GaAs substrate by Molecular Beam Epitaxy(MBE), with doping concentration of 5×1018 cm-3 and 2×1017 cm-3 respectively, which are well controlled on thickness and lattice perfection by controlling the temperature. Through parameter controlling, the stress of SiO2 passivation layer obtained by Plasma Enhanced Chemical Vapor Deposition(PECVD) is reduced, which therefore alleviates the bending of finger. The ohm contact resistivity is reduced to 0.8×10-7 ?/cm2 by optimizing the annealing temperature. The anode is fabricated by e-beam lithography and dry etching, and the trench is fabricated by controlled GaAs wet etching, then the complete planar Schottky diode is obtained. According to the calculation with I-U curve, the cut-off frequency of diodes can reach 1 THz. These studies can lay a foundation for following work.