Energy transfers and upconversion fluorescence spectroscopy in Tm³⁺-Yb³⁺co-doped AlF3-based flouride glass, excited at 970 nm, is experimentally investigated. The experimental results show that the concentration quenching of blue fluorescence at 476 nm is stronger than that of infrared light at 793 nm. In AYF and AZF glass, the optimum content of Tm³⁺for 476 nm emission is about 0.1 mol-%, while for 793 nm emission is 0.3～5 mol-%. The concentration quenching of Yb³⁺to upconvertion fluorescence is also observed. It is maybe due to the back-energy transfer from the 3F4 level of Tm³⁺to the 2F5/2 level of Yb³⁺.