In recent years, more and more applications or micro services have been deployed to the cloud. The virtual network is the basic guarantee in a cloud environment. Virtual Network Interface Cards (NICs) and virtual network bridges are built based on physical NICs in virtualization of NIC to construct the virtual network for virtual instances such as virtual machines and containers, and these virtual network devices are uniformly configured and managed. From the perspective of the virtual NIC and the virtual network bridge, the current popular virtualization technologies of NICs are sarveyed, classified, and compared in this study. Finally, the current situation and future development in NIC virtualization are analyzed.