Abstract :A Vehicle network is combination of mobile and sensor network features,vehicle network have high chances of DOS attack due to heavy traffic and infrastructure specification. Distributed Denial of Services (DDOS) Attacks in the network affects the communication of network and degrade the network reliability and performance. In Vehicular Ad Hoc Network (VANET) these DOS attack occur because of heavy trafficand slow down the communication. For prevent the DOS attacks, dynamic group based model is implemented. At the dynamic group based model method have mobility and stability analysis for generating the dynamic groups and identifying the virtual controllers. The communication within group analysed by the controller, the safe and unsafe nodes prioritize by the controller. Also the preventive node selection is performed by controller node. After the simulation, the results are comes clearly shows that the model method improves the communication throughput and reduces the communication loss. Keywords:-VANET, DDOS, Controller, Group Based,DOS, Communication.