Eu3+ doped Y2O3 nanocrystalline and bulk powders with small content of Ag+ were prepared by chemical self-combustion. An interesting phenomenon was observed: with an increase in Ag+ content the luminescent intensity of the nanosized crystal is enhanced at first and then maintains a stable level; however for the bulk powder there is no obvious change in the luminescent intensity when the Ag+ content is varied. The morphology and crystal structure were characterized by transmission electron microscopy (TEM) and X-ray Diffraction (XRD), respectively. Emission spectra were measured for nano- and bulk samples. The fluorescence decay curves for all the samples, including nanosized and bulk ones, either with or without Ag+, were measured. It is found that the lifetime for the nanosized sample with Ag+ is longer than that without Ag+, and the lifetime for the bulk sample has no change. From these experimental results wecome to the conclusion that the Ag+ ion may link with a surfice O2-, which has a free bond, then the surfice unsaturated dangling bonds can be eliminated. The elimination of surfice dangling bonds may cause the increase of luminescence efficiency of Eu3+ doped nanosized Y2O3.