A new kind of Tera-Hertz (THz) antenna, on-chip wide-flare-angle axial corrugated horn antenna, based on MEMS technology and focused ion beam (FIB) technology is presented in this paper. Optimal design for size and the number of corrugated structure together with exploring on the impact of the corrugated structure on electromagnetic radiation performance is studied in the research. The simulation results show the antenna gets an average gain above 15dB covered the frequency band (1050GHz∼1100GHz) with a return loss better than −17dB. The antenna has the advantages of miniaturization, high gain, and can be integrated on chip. It has important applications in the field of Tera-Hertz, especially in the direction of the THz communication integrated circuit.