With the appearance of intelligent information warfare， millitary intelligent decision-making has become a key link that can affect the outcome of war. On the basis of analyzing the new characteristics of intelligent decision support system in cloud computing environment， the comparative study of the traditional intelligent decision support system and the artificial neural network system is conducted in this paper respectively. An intelligent decision support system based on the parallel structure of expert system and artificial neural network in cloud computing environment is designed.The operation flow and reasoning process of the intelligent decision support system under the structure are analyzed， which provides a new idea and method for the research of military intelligent decision support system.