The Y0.95-xLaxVO4:5%Eu3+ (0 < x < 0.15) nanocrystalline powders were successfully synthesized by a mild hydrothermal method. Their photoluminescence properties were investigated under vacuum ultraviolet (VUV) and UV excitation. In comparison with YVO4:Eu3+ nanocrystalline powders, the luminescence intensity of Y0.925La0.025VO4:5%Eu3+ was improved under the excitation of 147 or 254 nm. Both the host absorption band in the VUV region and the excitation band centered at 262 nm in the UV region were enhanced by doping La3+ ions. Furthermore, the nanocrystalline powders exhibited some unusual luminescence behaviors compared to bulk YVO4:Eu3+. These phenomena were investigated and are discussed in detail.