This paper addresses when and how to adjust bandwidth allocations between uplink and downlink in a multi-service wireless network with bandwidth asymmetry under dynamic traffic load conditions. A new distributed multi-service admission control policy is developed first to guarantee the call level QoS requirements. When the traffic load brought by the calls of some specific classes in a cell exceeds the control range of the admission control, bandwidth re-allocation process could be activated and the admission control policy will try to meet the QoS requirements under the adjusted bandwidth allocation. The numerical results show that the QoS requirements of different call classes can be guaranteed under the dynamic traffic conditions while the system resources are utilized efficiently by using the proposed bandwidth re-allocation strategy.