The invention discloses a method for preparing ZnO thin films with buffer layers. The method includes steps of S1, cleaning monocrystalline silicon substrates and removing oil stain and impurities onthe surfaces of the monocrystalline silicon substrates; S2, utilizing Al targets as target materials, placing the monocrystalline silicon substrates in vacuum chambers of magnetron sputtering equipment, filling the magnetron sputtering equipment with sputtering gas Ar and reaction gas N2, and sputtering coating AlN buffer layers on the surfaces of the monocrystalline silicon substrates; S3, utilizing Al targets and ZnO targets as target materials, and sputtering coating composite buffer layers comprising AlN and ZnO on the surfaces of the AlN buffer layers; S4, utilizing ZnO targets as targetmaterials, and sputtering coating ZnO film layers on the surfaces of the composite buffer layers to obtain the ZnO thin films with the buffer layers. The method has the advantages that the ZnO film layers can be prevented from being in direct contact with the monocrystalline silicon substrates, and accordingly the crystallization quality of the plated ZnO film layers can be improved; integral procedures are simple magnetron sputtering film coating, are simple and are high in controllability and repeatability.