The invention relates to the technical field of network information communication, in particular to a reserved bandwidth adaptive adjusting method based on QoS. The method comprises the steps that a data transmission originator files an application to a route master, a data transmission originating host sends data which comprises extended headers, wherein IDQ is added to data packages, and a bandwidth adaptive adjusting module conducts queue treatment on the data packages according to the IDQ in the extended headers of the data packages and dynamically adjusts reserved bandwidths in real time according to the number of the data packages with the QoS requirement. The reserved bandwidth adaptive adjusting method based on QoS improves the utilization rate of network bandwidths, and compared with the prior art, efficiency of adjusting the reserved transmission bandwidths is obviously improved.