The Mobile Ad hoc Network (MANET) is a collection of portable devices establishing intermediate network without any access points. These MANETs plays a vital role in present wireless communication world. But these MANETs are highly vulnerable to attacks due to their characteristics such as the lack of infrastructure and wireless communication. This project deals with Ad Hoc On-demand Distance vector (AODV) routing protocol which is intended for use by mobile nodes in an ad hoc network. With the help of AODV protocol, the routing behavior can be analyzed by considering different parameters like throughput, delay, load and number of packets dropped using network simulator (NS2). There are different attacks, which damages the network like warm-hole, black-hole, jamming attacks etc. due to these attacks the performance of network is effected greatly. Out of all, black hole attack is one kind of routing distributing attacks and can bring great damage to the network. Here this project uses the AODV‟ s sequence number for identifying the Blackhole node in the network without using any extra packet formats. This project analyses throughput, delay, and load, number of packets dropped with and without attack in the MANET using NS2 simulator.