In order to obtain up-conversion luminescent materials with bright red emission, a series of Yb3+, Er3+, Mn2+-doped Gd2O3 microcrystals were prepared by simple chemical precipitation method, and their morphology, structure and luminescent properties were characterized. The results show that Gd2O3:10%Yb3+,1%Er3+ microcrystals exhibit a flower-like morphology, and the average diameter is 2.28 μm. After calcination at high temperature, the sample presents a cubic Gd2O3 structure with good crystallinity, and Mn2+ doping does not affect the morphology and crystal phase of the product. Under 980 nm near-infrared light excitation, Gd2O3:10%Yb3+,1%Er3+ microcrystals show orange-red luminescence, which corresponds to the 4F9/2→4I15/2 transition of Er3+. With the increase of Mn2+ doping concentration (molar fraction), the luminescence intensity of Gd2O3:10%Yb3+,1%Er3+, x%Mn2+ microcrystals first increases and then decreases, and the luminescence color gradually turns to red, which is consistent with the CIE color coordinate. At the same time, the up-conversion luminescence mechanism and the possible energy transfer process of Gd2O3:10%Yb3+,1%Er3+, x%Mn2+ microcrystals were analyzed according to the relationship between luminescence intensity and excitation power.