Based on the analyses of the research on existing reservation mechanism, advance reservation mechanism and malleable reservation mechanism, a dynamic advance reservation is introduced in this paper. Requests of advance reservation with fixed parameters, i.e. start time, end time and resource capability, may be rejected due to instantaneous peaks of resource utilization. Gaps between these peaks are too narrow for additional requests to fit in. As a result, the call acceptance rate of reservation would decrease dramatically, and the performance of resource may be reduced. In fact, many resource reservations for network applications need not fixed parameters, such as instantaneous transfer speed of large-scale data transfer. Its parameters can be modified according to resource status in order to fit gaps of resource. Particular admission control algorithm for this new type of reservation is provided too. Simulation shows that it can improve performance of resource reservation in terms of both call acceptance rate and utilization of resource.