The invention discloses a preparation method of plant ribosome. The preparation method comprises steps of preparation of wheat germ and a preparation step of a ribosome wheat germ extract. Specifically, the method comprises the following steps: preparing wheat seeds, drying, grinding and sieving the wheat seeds, collecting wheat powder granules, suspending, selecting, washing, cracking, carrying out ultrasonic treatment, carrying out oscillating treatment, drying, adding to a centrifugal tube, extracting, eluting, purifying, making an eluting curve, carrying out nucleic acid agarose electrophoresis, identifying an eluate, determining and collecting the wheat germ extract containing the ribosome to obtain a target object, and preserving the target object in liquid nitrogen for later use. The method disclosed by the invention solves the problems in the construction of a nucleic acid and ribosome in vitro combining system as well as material source and quality in antiviral activity screening of medicines. The plant ribosome prepared by the invention is pure in quality, relatively high in purity and complete in extraction, and is applicable to a virus TMV-RNA in vitro protein translation system as well as targeting drug screening, serving as a source of ribosome.