Ad Hoc network is a multi-hop temporary communication network of mobile nodes equipped with wireless transmitters and receivers without the aid of any current network infrastructure. [1] Due to lack of infrastructure support, security problem in these networks is a challenging issue. There exist previous work that studied the performance of the network under different types of security attacks. In this paper, complementary research by providing more realistic network scenarios such as various protocol used in the network is made. We consider two common types of attacks, black hole attack and gray hole attack, based on both AODV and DSR protocol respectively. We study the performance of the network in different number of malicious nodes and on different protocol via observing the metrics of a connection such as packet delivery ratio, throughput and end-to-end delay. The simulation result shows that the performance of the network based on both routing protocol is similar. It is should be noticed that the end-to-end delay is different in two routing network. The results enable us to put forward some suggestions to minimize the impacts of the above types of attacks in Ad Hoc network.