Abstract: With the rapid expansion of data center and the significant increase in network bandwidth, traditional software network protocol stack has high processor overhead and is difficult to meet the needs of many data center applications in terms of throughput, latency and other aspects. Remote direct memory access（RDMA）technology uses the ideas of zero copy, kernel bypass and processor function offloading to read and write remote host memory data with high bandwidth and low latency. Ethernet-compatible RDMA technology is being applied in data centers, and Ethernet RDMA NIC plays a crucial role in its deployment as the main functional bearer device. This overview analyzes from three aspects: architecture, optimization, and implementation evaluation. 1) We summarize the general architecture of Ethernet RDMA NIC and introduce the key functional components; 2) We focus on the optimization techniques in storage resources, reliable transmission and application-related aspects, including optimization of both connection scalability for NIC cache resources and registration access for host memory resources, optimization of congestion control, flow control and retransmission mechanism for lossy Ethernet to achieve reliable transmission, and optimization of different storage types in distributed storage, database system, cloud storage system, and multi-tenant performance isolation, security and programmability for data center applications; 3) Then we investigate different implementation and evaluation methods. Finally, the summary and outlook are given.