The invention provides a preparation method for a silicon intermediate infrared antireflection microstructure. The method comprises the following steps of first, designing a required etching pattern through drawing software; then, uniformly coating the cleaned silicon surface with a layer of ultraviolet photoresist; transferring a pattern designed by the drawing software to a silicon wafer coated with the photoresist by development of a developing solution through ultraviolet exposure, at the moment, coating the silicon wafer with a layer of gold film through an electronic beam evaporation method; and based on a wet etching principle, performing etching depth control by adjusting etching time and components of an etching liquid to obtain a height-controllable high-depth-to-width-ratio silicon micron array structure. The preparation method has the advantages of low cost, convenient processing, large and controllable etching depth and the like, and has a wide application prospect in the field of silicon intermediate infrared antireflection.