The invention discloses a preparation method of a polyhedral InBO3:Eu<3+> luminescent material. The method comprises the following step: by using indium nitrate or indium oxide as an indium source and potassium tetraborate, sodium borate or anhydrous lithium borate as a boron source, directly carrying out one-step reaction to prepare the hexahedral, octahedral or any polyhedral InBO3:Eu<3+> luminescent material. The method is simple, and has the advantages of mild reaction conditions and accessible raw materials. The polyhedral InBO3:Eu<3+> luminescent material has the advantages of favorable dispersity, uniform shape and higher luminescent intensity, and is applicable to the fields of display and development, light sources, medicine and the like.