This paper discuss Nigeria 330KV integrated power system coherent groups of generators for coherency based analysis method for network reduction to carry out transient stability analysis for multi-machine power system network. This method is based on the following different indices, the first one is inertia condition index and second one is initial power variation index. The coherency identification method has the ability to identify perfect coherent groups in a very simple way, so that the nature of the machines in the reduced order system is exactly similar to those of the full system. Each coherent group is replaced by a single machine using the method of dynamic equivalent construction. The proposed test system involves the integrated network consisting of 39 buses.