Among the luminescent materials, Y2O3:Eu3+ particles have the advantages of strong fluorescence emission, stable physical and chemical properties, and low toxicity. They are widely used in photoelectric displays, chemical fiber media, and other technological fields. However, due to the presence of a large number of hydroxyl groups on its surface, Y2O3:Eu3+ is strongly hydrophilic but poorly oleophilic, and because of that, it cannot be used in some special fields. In this research, hexadecyltrimethoxysilane (HDTMS) was used to modify the surface of the Y2O3:Eu3+ phosphor, and the experimental results indicate that the Y2O3:Eu3+ phosphor modified by HDTMS exhibits good hydrophobic and oleophilic properties. Moreover, its crystal structure does not change, and its fluorescence remains good. Additionally, the luminescence properties of the Y2O3:Eu3+ phosphor modified by HDTMS are not greatly affected. This study can provide a reference for the hydrophobic and oleophilic Y2O3:Eu3+ phosphor preparation and its application in organic media.