To address the issue of effective evaluation of Reconnaissance/Strike UAV(R/S UAV) combat effectiveness in complex battlefield environment,the main factors affecting the operational efficiency of the UAV are analyzed based on the UAV's operational process.A combat effectiveness evaluation model of R/S UAV is built by using the Dynamic Bayesian Network (DBN) method,and the calculation methods of the variable attribute level and the key parameters are given.The Netica tool is utilized to dynamically evaluate and simulate the combat effectiveness of the UAV,and the validity and feasibility of this model are proved.The model can serve as a reference for the combat operation and equipment development of the UAV.