Abstract.Video packets have different significances due to the video coding property. When delivering video data without priority strategy over the Internet, it will seriously degrade the received picture quality. This paper proposes an Unequal Priority Arrangement (UPA) mechanism for video transmission on differentiated service networks. UPA determines the priority of a video packet according to the evaluation from both temporal and spatial domains simultaneously. From the temporal domain, UPA evaluates the packet significance based on the temporal position of the packet and the induced error propagation if the packet is lost. From the spatial domain, UPA evaluates the packet importance based on its content, where the ratio of intra-refreshed MBs is used. Moreover, according to the video complexity, UPA can flexibly adjust the weight based on the evaluation results from temporal and spatial domains. Simulation results show that delivering video data with UPA on differentiated service network outperforms traditional temporal-based and spatial-based priority strategies up to 1.8 dB and 1 dB, respectively.