The TCP protocol is used by the majority of the network applications on the Internet. TCP performance is strongly influenced by its congestion control algorithms that limit the amount of transmitted traffic based on the estimated network capacity and utilization. In this work TCP Tahoe, TCP Reno, TCP New-Reno, TCPOM are considered. Also discussed how TCP reacts to the congestions and depending on the algorithm how the congestion window is minimized and how the packets are retransmitted. Simulation has been done with WAN type network analyzing the throughput, delay, packet delivery ratio, number of packet sent, number of packet dropped, number of packet received and performance of these TCP variants in order to discover which of them has a better performance. After analyzing with several TCP variant it was found that TCPOM exhibits a better performance with respect to throughput, delay, packet delivery ratio than the other TCP variants considered in this paper. TCPOM algorithm is explained in this paper and is compared with other TCP Variants algorithm like TCP Tahoe, TCP New-Reno, TCP-Reno and graph are plotted with respect to throughput, delay and packet delivery ratio. Simulation is done in NS3 environment  .