Horn antenna is one of the most widely used microwave antennas. With the increase in frequency and the requirement of lightweight, using the silicon micromachining process to make antennas horn becomes a promising implementation solution. Based on 44 GHz horn antenna requirements, this article demonstrates the design, material selection, manufacturing process, shear test result and the measurements. The horn antenna is made up of 27 layers of silicon wafers. The result shows the feasibility of the silicon micromachining process for realization of multi-layer horn antennas, and the solution can also be applied in the manufacture of 220GHz multi-layer terahertz silicon horn antenna.