Abstract: A new Fuzzy-logic based Dynamic Resource Allocation algorithm (FDRA) used for QoS control is proposed in this paper. In the hierarchically distributed architecture with multiple Bandwidth Brokers (BB), using sliding window and sliding pointer based mechanism, when the allocated resource is in short, a request is issued by the distributed BB to the centralized BB for additional resource. When the resource kept by a distributed BB is over the actual need to some extent, some allocated resource will be released with hysteresis. The size of additional allocated resource and released resource is determined by the centralized BB and the distributed BB respectively. The determination is concluded with a fuzzy logic algorithm taking into account of the current network load status. In order to improve the effectiveness of the decision, a new method of fuzzy mapping function generation is proposed, which is based on the statistical characteristics of the data sources. Simulation results show that the proposed algorithm is superior to the existing ones.