Based on ANSYS, finite element simulation calculation model of mid-infrared solid laser was established, and modal parameters, such as natural frequency and vibration mode were gained through modal analysis. Combined with non-contact vibration measurement technology, the vibration modal test platform was set up, and the reliability of the modal simulation model was verified by the comparison with the test. Then, on the basis of modal simulation, the vibration characteristics of laser optical crystal assembly was studied emphasisly under condition of sinusoidal frequency sweeping vibration of vehicle through response analysis, and equivalent stress, total mechanical strain, relation between displacement and excitation frequency can also be obtained. Last, the key positions that affecting the vibration reliability of laser were analyzed and the results provide useful reference for improving design. The results indicate that there are four natural frequencies and modes in middle infrared solid laser using bottom fixed constraint, within 2 000 Hz and the experimental results of the modal agree with simulation results, and the natural frequency error is less than 8%. The maximum total mechanical strain and equivalent stress appeared at the edge of the input mirror under the condition of vehicle frequency sweeping vibration. The axial displacement along the optical crystal assembly is the largest and its value is about 0.14 mm.