Aiming at the problems of effectiveness evaluation of space-based information support equipment system, a method of operational effectiveness evaluation of space-based information support equipment system based on Bayesian network is proposed. The simulation platform based on system dynamics is constructed to obtain simulation data, and the Bayesian network structure learning algorithm based on search and the expectaion maximization parameter learning algorithm are used to learn the data samples to construct the Bayesian network model. Forward reasoning, cause-and-effect tracing reasoning, and stage analysis reasoning were used to analyze the operational effectiveness. The model was used to analyze the relationship and influence degree of many factors in the space-based information support equipment system in the combat scenario of long-range precision attack on moving ship targets in the direction of the sea. The simulation results show that the method is effective and feasible in the operational effectiveness evaluation of space-based information support equipment system, and can provide technical support for the effectiveness evaluation of weapon equipment system.