A Wireless ad-hoc network is a short-lived network set up by wireless mobile computers or nodes moving randomly in the places that have no network infrastructure. While the nodes communicate with each other, they assist by forwarding data packets to other nodes in the network. Thus the nodes discover a path to the destination node using routing protocols. Though, due to safety measures of the routing protocols, wireless ad-hoc networks are undefended to attacks of the malicious nodes. One of these attacks is the Gray Hole Attack against network integrity absorb all data packets in the network and data packets do not connect with the destination node. As a result data loss will occur. There are many detection and protection procedures to reduce the intruder that perform the gray hole attack. In this paper, simulate the gray hole attack in AODV This paper analyze the effect of gray hole attack on MANET and detection of these attacks by using IDS.