在無線車載網路中，緊急訊息如何有效地廣播一直以來是一個重要的議題。本篇論文提出一個動態分割協助廣播協定(DPAB)，透過調整車輛間控制封包回傳的訊號強度，藉以評估網路車輛密度以找尋最佳的代傳車輛，並減少干擾訊號，進而達到節省無線傳輸資源與提高封包成功傳輸率。最後透過數學分析與實驗模擬的方式驗證本論文；實驗結果也顯示，DPAB與其他作法比較下有較好的One Hop Delay與Packet Delivery Ratio。 Effectively broadcasting emergency messages in vehicular ad hoc networks (VANETs) is an important issue in VANETs. This paper proposes a Dynamic Partition Assisted Broadcast (DPAB) protocol to effectively broadcast emergency messages in VANETs. Adjusting the power level of control messages to estimate the network density and dynamically partition a transmission range into segments are the major techniques in DPAB. To do so can not only find the best vehicle in the furthest possible segment to relay the emergency messages in the network, but also can reduce the interference among vehicles to save the network resource and increase the packet delivery ratio. Based on the mathematical analyses and network simulations, the proposed protocol, DPAB, has a significant performance against the related work in one hop delay and packet delivery ratio.