Lead halide perovskite nanocrystals (NCs) are still a popular subject in the field of luminescence because of their high photoluminescence quantum yield (PLQY) and colour tenability through anion exchange reactions or quantum confinement. We investigated the structure and luminescence properties of the mixed halide perovskites CsPbBr2I NCs with annealing temperatures. The results showed that the average grain size of CsPbBr2I increased with increasing the temperature from 300 to 440K, and the morphology changed above 380K. The normalised PL spectra of CsPbBr2I NCs had an obvious blue-shift, and then displayed a slight red-shift with increasing annealing temperature. In addition, the PL intensities, peak energies, and bandwidths of the NC films as a function of temperature were discussed in detail.