In order to avoid high frequency shooting load causes the trucked anti-aircraft gun’s structure vibrates violently during the launch process and to improve the anti-aircraft gun’s firing accuracy, research the modal analysis of trucked anti-aircraft gun fire system. Establish the structure topology and finite element analysis model of the anti-aircraft gun fire system, using the modal analysis in ANYSYS Workbench software to obtain the fire system’s natural frequency and vibration mode. The finite element modal calculation results are verified by modal test. Verification results show that this research can provide the reference for the dynamic analysis and structure optimization design of the anti-aircraft gun fire system.