Tm3+-Er3+-Yb3+-codoped transparent oxyfluoride glass ceramics containing NaYF4 nanocrystals are fabricated. The formation of NaYF4 nanocrystals in the glass ceramics is confirmed by X-ray diffraction. Absorption spectra and upconversion fluorescence emission spectra under 980 nm excitation are measured. Intense blue (476 nm), green (520 and 550 nm) and red (651 and 668 nm) emissions are simultaneously observed. Upconversion blue emission is corresponding to the 1G4→3H6 transition of Tm3+; Upconversion green emissions are corresponding to the 2H11/2→4I15/2 and 4S3/2→4I15/2 transitions of Er3+, respectively; Red emissions are corresponding to the 1G4→3H4 of Tm3+ and 4I9/2→4I15/2 of Er3+. Under the invariable concentrations of Tm3+ and Yb3+, the diversification of tricolor light integral intensity is investigated by changing concentrations of Er3+. To obtain upconversion fluorescence mechanisms, upconversion fluorescence intensity versus LD pump power are analyzed in view of energy levels of rare-earthions.