Abstract: Based on the large-scale path loss model for wireless communications, a Vehicular Ad hoc NETwork (VANET) in highway scenarios is modeled as a geometric random graph, the concept of effective networking area in VANET is proposed, the quasi-linear topological features of VANET is analyzed, the probability of nodes which have at least k neighbors located within its radio coverage is also derived, based on the assumption that the space headway under free flow conditions follows an approved traffic flow distribution. Experimental results demonstrate that the proposed algorithm, with the philosophy of thinking in probability, is an effective computational method on the node degree of a vehicular ad hoc network in highway scenarios.