Yb3+-Er3+ co-doped Na2O-GeO2-PbO glass suitable for developing optical fiber lasers and amplifiers has been fabricated. The energy transfer efficiency from Yb3+ to Er3+ was investigated in the glasses with different Yb3+-Er3+ concentration ratios and the maximum energy transfer efficiency was found to be 67% at the Yb3+-Er3+ concentration ratio of 5:1. Subsequently, the studies of upconversion emissions in the visible range were performed. An intense green together with a relatively weak red emission was observed under the excitation of 976nm diode laser. The quadratic dependence of the green emission on excitation power indicates that a two-photon absorption process occurs under a 976nm excitation. However, for the red emission the slope of log-log plot of integrated intensity versus pump power declines with increasing Yb3+ ions content, indicating it is not resulted from a biphotonic process.