The near-infrared (NIR) quantum cutting (QC) nanoparticles (NPs) beta-NaYF4:Er3+ are prepared by coprecipitation method. Three-photon NIR QC luminescence at 1520 rim (I-4(13/2) -> I-4(15/2)) is obtained under the excitation of 519 nm (I-4(15/2) -> H-2(11/2)). The corresponding QC efficiency eta(QC) calculated from the luminescence decay curves reaches as 242.59%. Furthermore, three-photon NIR QC luminescence is enhanced by the localized surface plasmon resonance of Ag nanocubes (NCs). The influence of Ag NCs concentration on three-photon QC luminescence is investigated, and the results show that the optimal concentration of Ag NCs is 0.10% with the enhancement factor reached a maximum as 2.86. Our study may have potential application as a QC layer to improve the photovoltaic conversion efficiency of germanium (Ge) solar cells.