The new Er3+/Yb3+-codoped 70TeO2-5Li2O-10B2O3-15GeO2 glass was prepared by the technique of high-temperature melting. The thermal stability, absorption spectra, fluorescence spectra and upconversion spectra were measured and investigated. The oscillator strength, spontaneous emission probability, radiative lifetime and emission branching ratio of several Er3+ transitions were calculated according to the Judd-Ofelt theory. It is found that this glass has good thermal stability, broad FWHM and large stimulated emission crosssection. The three upconversion emissions at about 532 nm, 546 nm and 659 nm, corresponding to the 2H11/2→4I15/2, 4Ss/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+, respectively, were simultaneously observed excited by 970 nm LD. The results show that this glass may be a suitable material for optical amplifiers and practical upconversion fiber optical devices.