A reflective fluorescence temperature sensor based on the dual-granularity CdSe/ZnS doped quantum dots (QDs) thin films is designed. The CdSe/ZnS doped quantum dots thin films with the emitting wavelengths of 540 nm and 610 nm are applied to the system as a key device. The optical characteristics of photoluminescence (PL) spectra with the change of temperature between 30 ℃ to 100 ℃ are studied, such as the peak wavelengths of PL spectra, the energy bandgaps of the QDs, the peak intensity of PL spectra and the self-referenced intensity of PL spectra. Results show that, the peak intensity of PL spectra decreases gradually with the increase of temperature; the peak wavelengths of PL spectra, the energy bandgaps of the QDs and the self-referenced intensity of PL spectra vary linearly with the temperature; the peak intensity of PL spectra can be denoted by exponential function of the temperature; the stability of the self-referenced intensity of PL spectra shows good during heating and cooling; the red shift of the the peak wavelengths happens with the increase of the temperature, and the average resolution of the designed reflective fluorescence QDs temperature sensor can reach 0.055 nm/℃.