75TeO2-20ZnO-(3-x)La2O3-2Yb2O3-xHo2O3(TZLH x,x=0,0.2,0.4,1,2 mol %),75TeO2-20ZnO- (4.6)La2O3-0.4Ho2O3 glasses were prepared.Effect of Ho2O3 content on upconversion properties of Ho3+/Yb3+ co-doped TZLH glasses have been investigated under 975nm excitation,and upconversion luminescence mechanisms were analyzed.The result shows that the upconversion intensity is enhanced largely with increasing Ho2O3 content and has a maximum at 0.4mol% Ho2O3 content and then decreases with an increase in the Ho2O3 content.Rate equations based on energy levels of Yb3+ and Ho3+,and upconversion mechanisms were developed.By calculating the rate equation to fit the measured fluorescence decay,coefficients of the energy transfer rate CDi (i=2,3,4）between Yb3+ and Ho3+ were obtained.