This study successfully prepares a transparent KLu₂F₇∶Er³⁺/Yb³⁺ nano-composite glass ceramics using a high melt quenching method. X-ray diffraction was used to characterize the types of nanocrystals precipitated from the glass, and the highest crystallinity was up to 28%. A spectrophotometer was used to verify the optical transmittance of the prepared glass ceramics (approximately 89%). Under 980 nm laser pumping, the upconversion luminescence of the glass ceramic sample was increased by 847 times, and it was found that both the upconversion green and red light belongs to a two-photon process. The fluorescence temperature measurement performance of thermal coupling energy levels ²H_11/2 and ⁴S_1/2 of Er³⁺ was studied using the fluorescence intensity ratio technique in the range of 313-553 K, with the corresponding absolute and relative temperature sensitivity reaching 11.03×10^-4 K^-1 and 738.45 T^-2·K^-1, respectively. The results provide a data reference for exploring the properties of fluoride-based glass ceramics in the field of high-temperature sensing.