The invention relates to a 0.5THz corrugated horn antenna and a preparation method using an MEMS technology. The 0.5THz corrugated horn antenna and the preparation method using the MEMS technology are applicable to a terahertz-band imaging system or a short-distance terahertz communication system. The 0.5THz corrugated horn antenna comprises an expanded horn, V-shaped corrugated grooves, locating grooves and a step on the throat portion of the horn, wherein compared with a waveguide, the horn can improve radiation efficiency and rotation symmetry of a directional diagram; the V-shaped corrugated grooves are used for cutting off a surface current, the gain is effectively increased, and influence of metal structures around the 0.5THz corrugated horn antenna on the performance of the 0.5THz corrugated horn antenna can be reduced; the locating grooves can ensure accurate alignment when installation butt joint of the 0.5THz corrugated horn antenna is carried out; due to the step on the throat portion of the horn, the design freedom of the structure of the horn can be remarkably improved, influence of the alignment error between an upper layer silicon chip and a lower layer silicon chip on the performance of the 0.5THz corrugated horn antenna can be reduced, and the processing yield is improved. According to the thinking design, the 0.5THz corrugated horn terahertz antenna designed and obtained through the thinking is good in applicability, an array can be easily formed, and fixation and testing can be easily carried out. The 0.5THz corrugated horn antenna works within the 450GHz-530GHz frequency band, a standing wave of the 0.5THz corrugated horn antenna is lower than 1.6, the in-band gain is larger than 15dB, and the maximum gain can reach 16.6dB.