NS3 is an open source Network Simulator used in research and educational feild.NS3 is an open source free software freely and publicly available for research and development. It is licensed under GNU GPLv2 license. The main aim of this NS3 project is to give network researchers the open simulation environment to test their network protocols so that these protocols gives same performance in the real time screnario.Ns3 is developed by Tom Henderson, George, Sally Floyd and Sumit Roy. The team received funding from US National Science Foundation(NSF) for the development of NS3. NS3 is written from the scratch in c++ programming language. Waf build systems and framework for generating Python bindings are contributed by Gustavo Carneiro. Today NS3 is used by many researchers to perform their research in networking filed. Journals like IEEE, ACM, IJCA etc accepts the result simulated using NS3 simulator. New protocol can be written and tested in NS3 by using c++ language with an extension of .cc, after compiling these .cc files NS3 generates .pcap file and .tr files. These .tr files generated by the NS3 can be analyzed to get the throughput, delay, jitter, packet delivery ratio for new protocol developed. Trace file format of NS3 is totally different from that of trace format of NS2. In this paper a new trace file analyzer is developed using Java so that researcher can spend much of his time and efforts in developing a new protocol than analyzing a trace file. This paper also discussed the trace file format of NS3.Similar project called tracemetric is developed but it is not installed correctly on every machine and is not able to read the .tr file takes too long.