In order to tune the fluorescence performance of Yb∶YAG crystal to be better applied in high-energy pulse lasers, based on density functional theory and crystal field theory, the electronic structure and spectroscopic properties of doped Yb∶YAG crystal were theoretically calculated. The fluorescence properties of Yb∶YAG crystal under the different types and occupation sites of particle doping were analyzed. According to the theoretical results, the crystal growth experiment was carried out, and the samples were prepared to verify the fluorescence performance. The results shows that, the tuning methods of Yb∶YAG crystal fluorescence lifetime and other parameters are mastered through the above process, that is, the fluorescence lifetime of Yb∶YAG co-doped with Cr decreases from 1.18 ms to 0.94 ms. This work lays a theoretical and experimental foundation for Yb∶YAG crystal to realize the application of high-energy pulsed laser.