Abstract: This paper introduces the main production process of the domestic horn antenna plate, points out the shortcomings of the production process and puts forward the method of batch-producing this kind of parts by using a new precision die-casting process. Taking a double ridge horn antenna plate as the casting prototype, a set of die-casting mold is designed. The key points of the die-casting mold design are described in terms of raw materials selection, parts structure analysis, casting process design and mold structure design. And the mold is optimized based on FLOW-3D simulation software. Process parameters are set up to produce trial casting samples and the die-casting mold is fine-tuned and optimized according to its surface and internal defects. The post-processing method of the parts is described. Finally, the tests of environmental adaptability and electrical properties for the assembled horn antenna plate are carried out, which verifies the effectiveness of the new process and the rationality of the mold design. The work in this paper contributes to the process innovation of the horn antenna plate and the design of the die-casting mold for similar thin-walled aluminum parts.