MANET (Mobile Ad hoc network) is the emerging and most demanding technology of wireless network. Because of self-deliberate property, the network points behave as router or source and the nodes keep moving freely in the network area. MANET plays a significant role in connectionless infrastructure. Securing a network is the fundamental issue in MANET for securing the susceptible information from hackers. MANET has different attacks that are routing protocol attacks. The sinkhole is known as the severe one from all the attacks in MANET. It generally attracts the neighbor’s nodes towards itself and transmits the bogus or fake routing path. This attack decreases the network lifetime and increases the network overhead by boosting energy consumption and later destroys the network.In the proposed work, the routing protocol is being optimized by utilizing ACO (Ant Colony Optimization) with NN (Neural Network) for achieving enhanced performance as compared to existing work. Different parameters, namely, Bit error rate, throughput, an end to end delay and energy consumption are used for calculating the performance of the proposed work in MANET or to check the effect of Sinkhole attack. The environment created by simulating the work has 50 to 100 nodes. The width and height of the network are 1000 nodes.