In order to improve the accuracy of firepower damage assessment, an army long-range firepower damage effectiveness assessment model was established. Based on the analysis of target damage information sources and the construction of damage criterion, the Bayesian network is taken as the theoretical basis, and the maximum likelihood estimate (MLE) and expert correction method are used to determine the network parameters of the model, and the damage level evaluation formula is solved, and the applicability of the model is proved by actual data. The results show that the model can accurately evaluate the damage level of the army's long-range firepower to the target, and provide support for accurate evaluation of the army's long-range firepower damage effectiveness.