In mobile Ad-Hoc networks, each node of the network must contribute in the process of communication and routing. However, this contribution can expose the network to several types of attackers. The security of mobile ad hoc networks is an open research topic and a major in terms of their vulnerability to various attacks, such as black hole, Sybil ... etc. In this article, we analyze the attack black hole (black hole) in ad hoc networks using as AODV routing protocol. In a black hole attack, a malicious node impersonates a legitimate node, manufactures forged responses with a number of high sequence and thus forces the victim node to select it as a relay. We are interested in a first time to study the impact of dishonest nodes on the network, and then we will simulate black hole attack using two simulator NS2 and OPNET.