Safety application is very important in vehicular ad-hoc networks. Safety-related message priority is classed based on message urgency. In this paper, a spatiotemporal-based dynamic priority scheduling scheme is proposed. A spatial-temporal relevance function is introduced to represent the priority, which decreases as distance and duration increase in the message dissemination. Meanwhile, the distribution of a urgency message is limited to a bound duration and spatial area. Analyses and simulations show that the spatiotemporal-based dynamic priority scheduling is of a significant performance improvement in decreasing the network load in high density and increasing the transmission distance in the low density over the method using the fixed priority with the maximum delay threshold.