In recent years, novel metal halide scintillators have shown great application potential due to their tunable emission wavelength, high X-ray absorption, and high luminescence efficiency. However, poor stability and complex device packaging remain key issues for metal halide scintillators, making it difficult to achieve high-resolution and flexible X-ray imaging applications. To address the above issues, a multiprocessing strategy was introduced to prepare Cs 3 Cu 2 I 5 @PMMA scintillator films for long-term stable application, mainly undergo different annealing treatments to make Cs 3 Cu 2 I 5 crystals to accurately nucleate and then grow in-situ in the PMMA matrix. Then, a series of characterization results illustrate that the prepared Cs 3 Cu 2 I 5 @PMMA scintillator films have high crystallinity, uniform size, excellent flexibility, high stable photoluminescence (PL) and radioluminescence (RL) performance, and high-resolution X-ray imaging capability. Most importantly, Cs 3 Cu 2 I 5 @PMMA scintillator films can not only provide clear and accurate imaging recognition of objects with different complex structures but also maintain stable X-ray imaging quality within 60 days and can achieve flexible X-ray imaging. Therefore, we have provided an effective strategy for producing high-quality scintillator films to meet the multidimensional needs of a new generation of scintillators.