With the development of military technology, the large scale war, network war and the Group war have gradually become the main form of future wars. This brings a new demand of large scale multi-sensor data fusion and super-computing capacity for information fusion system. Aiming at the shortcomings of traditional information fusion system, a new information fusion system is designed based on cloud computing. The functional module and software architecture of the new information fusion system are presented then. At the end of this paper, the operational workflow of the system under a certain operation scenario is analyzed. Compared with the traditional information fusion system, the cloud-based information fusion system has superiorities in data throughput, computing capability and system flexibility. It can meet the needs of future war and provides a theoretical support for the built of information fusion system of the future.