The invention relates to a method for preparing rhodium carbonyl. The method is characterized by comprising the following steps: by adopting metallic rhodium powder or granule as a raw material, carrying out carbonylation synthesis reaction on the metallic rhodium powder or granule and CO; condensing a generated rhodium carbonyl gas to obtain a rhodium carbonyl crystal particle. The method for preparing rhodium carbonyl, which is disclosed by the invention, can be used for effectively preparing rhodium carbonyl and has the advantages of simple process and large-scale production.