Big data" has become a hot spot of the times, and the processing of big data is inseparable from Data Center Networks (DCN). As the infrastructure of the information era, data center networks provide a variety of network services and become key support technologies for future Internet/Cloud computing services and applications. In the process of soliciting data and using data, the performance of the data center network is very important. In the data center network communication process will produce a large number of TCP flows, if you can speed up the transmission of TCP flows, you can greatly reduce the response time, bring economic benefits; the other hand, if you can't properly control the data center network appears With a large number of TCP streams, there will be network congestion. This paper analyzes the problem of TCP fairness in data center network theoretically, designs the network topology according to the characteristics of the data center network transmission process, uses NS2 simulation platform to carry out experiments, and simulates and analyzes TCP fairness according to the principle of maximum and minimum fairness. The relationship between sex and bottleneck bandwidth, network parameters such as RTT, and the number of flows and other factors, and finally gives relevant conclusions.