Tm3+/Er3+/Yb3+ codoped tellurite glasses(TeO2-ZnO-La2O3) are prepared by conventional melt-quenching method.The absorption spectra and upconversion luminescence spectra of the glasses are measured,and the upconversion luminescence mechanisms are analyzed.The results show that the intense red(662 nm),green(525 nm,546 nm) and blue(475 nm) upconversion emissions of the prepared tellurite glasses are simultaneously observed at room temperature under 975 nm laser diode(LD) excitation.Upconversion red and green e...